US Postal Research Articles

How Have American Migration Patterns Changed in the COVID Era?

ABSTRACTSince the onset of the COVID‐19 pandemic, popular accounts and new data have contributed to a narrative of major deconcentration to less dense neighborhoods and smaller regions. In turn, this informs long‐range regional growth policies. Pandemic‐period deconcentration is thought to be fueled by the constraints of restricted public activity and the widespread emergence of remote and hybrid work. This paper develops a regression model of the push‐and‐pull factors of interregional migration using 2015–2019 origin‐destination data and compares it with newly‐available US Postal Service address change data, which provide monthly in‐ and out‐moves at the relatively fine ZIP‐code level. Model results highlight the continued pull of job growth for migrants and find that household overcrowding—as a regional measure of housing supply—is more closely linked to migration than housing cost. Address change data covering the pandemic's peak confirm the increase in large‐region out‐migration and a corresponding influx in small places. However, in the later stage of the pandemic from July 2021 to June 2022, the highest population regions returned to their previous migration trends and dense ZIPs rebounded further to their previous migration levels, suggesting that a shorter‐term, COVID‐induced deconcentration process differed from the background trend of moves down the urban hierarchy.

Potential Impact of USPS Mail Delivery Delays on Colorectal Cancer Screening Programs.

Colorectal cancer is the second-leading cause of cancer deaths in the United States. Fecal immunochemical tests (FITs) are a primary means of colorectal cancer screening at some health care institutions because of scheduling backlogs for screening, diagnostic, and surveillance endoscopies. However, delays in mail delivery can impact timely analysis of samples, possibly leading to false-negative results and the need for repeat tests. Some patients might be unwilling to submit another test when informed that an earlier sample cannot be reliably analyzed, resulting in a missed opportunity for screening. The Jesse Brown Veterans Affairs Medical Center has experienced some success through contacting the local US Postal Service (USPS) to avoid these delays; however, the problem often unpredictably recurs with USPS staff turnover. Laboratories and health systems experiencing delays should first ensure that prepaid envelopes have the correct postage and that their USPS accounts are properly funded, to confirm that insufficient funds are not contributing to the delayed deliveries. Adding additional language to the preprinted envelopes, such as "time-sensitive," may also be helpful. Asking patients to drop off test kits at the laboratory or using private letter carriers is not feasible in some communities. Other strategies include establishing a drop-off box at clinic offices or considering other screening methods, such as colonoscopies or flexible sigmoidoscopies. Clinicians who work in health care systems that use FIT kits need to be aware of the impact that local USPS delays can have on the reliability of FIT results. Health systems should be prepared to implement mitigation strategies if significant delays with mail delivery are encountered.

Construction of residential histories to estimate long-term environmental exposures in the California Teachers Study cohort.

Environmental epidemiologic studies using geospatial data often estimate exposure at a participant's residence upon enrollment, but mobility during the exposure period can lead to misclassification. We aimed to mitigate this issue by constructing residential histories for participants in the California Teachers Study through follow-up (1995-2018). Address records have been collected from the US Postal Service, LexisNexis, Experian, and California Cancer Registry. We identified records of the same address based on geo-coordinate distance (≤250 m) and street name similarity. We consolidated addresses, prioritizing those confirmed by participants during follow-up questionnaires, and estimating the duration lived at each address using dates associated with records (e.g., date-first-seen). During 23 years of follow-up, about half of participants moved (48%, including 14% out-of-state). We observed greater mobility among younger women, Hispanic/Latino women, and those in metropolitan and lower socioeconomic status areas. The cumulative proportion of in-state movers remaining eligible for analysis was 21%, 32%, and 41% at 5, 10, and 20 years post enrollment, respectively. Using self-reported information collected 10 years after enrollment, we correctly identified 94% of movers and 95% of non-movers as having moved or not moved from their enrollment address. This dataset provides a foundation for estimating long-term environmental exposures in diverse epidemiologic studies in this cohort. IMPACT: Our efforts in constructing residential histories for California Teachers Study participants through follow-up (1995-2018) benefit future environmental epidemiologic studies. Address availability during the exposure period can mitigate misclassification due to residential changes, especially when evaluating long-term exposures and chronic health outcomes. This can reduce differential misclassification among more mobile subgroups, including younger women and those from lower socioeconomic and urban areas. Our approach to consolidating addresses from multiple sources showed high accuracy in comparison to self-reported residential information. The residential dataset produced from this analysis provides a valuable tool for future studies, ultimately enhancing our understanding of environmental health impacts.

Development of a Pharmacy Point-of-Dispensing Toolkit for Anthrax Post-Exposure Prophylaxis for Allegheny County Postal Workers.

The Centers for Disease Control and Prevention (CDC) and the US Postal Service (USPS) consider anthrax to be a potential threat to USPS workers. A county health department-owned pharmacy supports local USPS response in the event of an exposure. The pharmacy team identified the need to review and update the local anthrax response plan. A Pharmacy Point-of-Dispensing Toolkit and response plan for initial 10-day post-exposure antibiotic prophylaxis was developed for use by a local health department in the event of a mass anthrax exposure at a US Post Office sorting facility. The pharmacist's role in medical countermeasures planning for anthrax exposure is also discussed to illustrate how pharmacists' medication expertise can be utilized. The CDC's Public Health Preparedness Capabilities: National Standards for State and Local Planning framework and inputs from an interprofessional stakeholder team were used to develop a Medical Countermeasures Response Plan and Implementation Toolkit for mass point-of-dispensing (POD) in the event of an anthrax exposure. Stakeholders attended a USPS Community Partner Training event where additional revisions to the toolkit were made. The toolkit and standing order are now implemented at the local health department to be reviewed and updated on a yearly basis by health department leadership. Pharmacists can use their medication expertise and experience with patient education to design emergency response plans focused on increasing patient safety and medication adherence. Pharmacists should be involved in emergency response and medical countermeasures planning that involve medications.

An Economic Case against Public Banking, and a Case for It

Abstract In this article, we examine the economics of public consumer banking in the United States. Public expenditures on consumer banking can take the form of price subsidies or direct provision. The economic case for price subsidies is weak because the evidence suggests most unbanked consumers would prefer a cash grant. The economic case for public provision is also weak because the existing market failures in banking are better remedied by regulation. The exceptions to this rule are check cashing and related payment services, which could be supplied by the US Postal Service (USPS) at a lower cost than private providers. On the other hand, economic arguments for the superiority of cash transfers presume that the institutional infrastructure exists to deliver them. But an effective infrastructure for public transfers does not exist in the United States and is only possible with universal ownership of payment accounts, which in turn requires some form of public subsidy or provision. We suggest one path forward: expand the financial services currently offered to federal beneficiaries—such as Social Security recipients—by the Treasury.

AGING AND MASS MARKETING FRAUD: EVIDENCE ON REPEAT VICTIMIZATION USING PERPETRATOR DATA

Abstract Fraud complaint data indicates that adults in their 70s and 80s experience significantly greater fraud losses than middle aged and young adults, however older adults are less likely to self-report victimization overall. One explanation for older adults’ relatively higher financial losses may be that they experience a greater incidence of repeat victimization. In this study, we examine the relationship between age and repeat mass marketing fraud using a novel dataset of nearly one million US mail fraud victims. The data come from four mail fraud enterprises that were investigated by the US Postal Inspection Service and that ran overlapping scams between 2000 and 2018. The perpetrators collected information on victims (name, address, age) and how often they paid money in response to scam solicitations. Datasets were merged, cleaned, and deduplicated. We use a Prentice-Williams-Peterson adaptation of a Cox proportional hazards model to estimate the effect of age on the likelihood of experiencing a subsequent victimization, controlling for the number of prior victimizations. Compared to victims in their 50s, victims aged 70-79 and 80-89 had a 9% greater risk of experiencing another victimization, whereas victims in their 20s had a 24% lower risk of experiencing another victimization. Logistic regression analyses indicate that adults in their 70s and 80s are significantly more likely than those younger than 50 to experience victimization by multiple types of mail scams. This is the first study to use perpetrator data, rather than self-report, to show that older adults face a greater risk of repeat fraud victimization.

Identifying a National Cohort of Medicare Beneficiaries Residing in Assisted Living Settings: An Updated Method.

Present an updated approach to identifying Medicare beneficiaries residing in licensed assisted living (AL) settings in the United States. Retrospective cohort study using a national list of licensed AL settings, US Postal Service (USPS) data, and enrollment, claims, and assessment data from the Centers for Medicare and Medicaid Services. A total of 403,326 beneficiaries residing in 29,905 licensed AL settings. We identified every ZIP+4 code affiliated with each AL address. We then identified all of the Medicare beneficiaries with that ZIP+4 on January 1, 2019, and excluded beneficiaries in nursing homes and hospitals on that date. We identified beneficiaries who were "definitively" and "very likely AL residents"according to the number of addresses corresponding to the ZIP+4 in the USPS data, the capacityof the AL setting, and the presence of a claim or assessment indicating services were delivered inAL. We compared beneficiaries excluded during our new capacity restriction step (ie, "possibly neighbors")to those included as being "definitively" and "very likely AL residents" using standardized mean differences. The cohort excluded (ie, "possibly neighbors") using our new step in the identification process appears to be younger and healthier than the cohorts we include as being "definitively" and "very likely AL residents." In addition, the cohort we identified through our added step of supplementing with claims and assessment data have similar demographics to the other cohorts we include, although they appear to be in poorer health. Leveraging licensed capacity information and supplementing with claims and assessment data produce greater confidence in the ability to accurately identify AL residents using ZIP+4 codes reported in Medicare administrative data.

Postal banking and US cash transfer programs: a solution to insufficient financial infrastructure?

Direct cash transfers to households during the COVID-19 pandemic, including relief checks and Child Tax Credit payments, were delayed by weeks for recipients without bank accounts and were not received by many non-filers who lacked the time or resources to complete necessary paperwork. A postal banking system has the potential to expand access to financial infrastructure and enable the rapid distribution of resources to households in need during economic downturns – often the same households that are currently excluded from the financial system. This paper examines the history of the US Postal Savings System and the feasibility of a return to postal banking using evidence on the socioeconomic and spatial patterns of financial exclusion. We find that postal banks would be well positioned to compete with both alternative and conventional financial institutions, address issues with physical branch access, and improve outreach to vulnerable populations.

Direct Marketing via US Postal Service’s Every Door Direct Mail Program

In this paper I describe the US Postal Service’s Every Door Direct Mail program which delivers postcards inexpensively to residents within a ZIP code. Extension educators interested in making the most of their advertising dollars can use the EDDM program advantageously. Best practices for advertising campaigns employing this direct mail option are provided.

What Is the Geographic Distribution and Density of Orthopaedic Advanced Practice Professionals in Rural Counties? A Large-database Study.

Advanced practice professionals, including physician assistants (PAs) and nurse practitioners (NPs), play an important role in providing high-quality orthopaedic care. This role has been highlighted by projections of nationwide shortages in orthopaedic surgeons, with rural areas expected to be most affected. Given that approximately half of rural counties have no practicing orthopaedic surgeons and that advanced practice professionals have been shown to be more likely to practice in rural areas compared to physicians in other medical disciplines, orthopaedic advanced practice professionals may be poised to address orthopaedic care shortages in rural areas, but the degree to which this is true has not been well characterized. (1) What percentage of rural counties have no orthopaedic caregivers, including surgeons and advanced practice professionals? (2) Is the density of advanced practice professionals greater than that of orthopaedic surgeons in rural counties? (3) Do orthopaedic advanced practice professionals only practice in counties that also have practicing orthopaedic surgeons? (4) Are NPs in states with full practice authority more likely to practice in rural counties compared with NPs in restricted practice authority states? We identified orthopaedic surgeons and advanced practice professionals using the 2019 Medicare Provider Utilization and Payment Data, as this large dataset has been shown to be the most complete source of claims data nationwide. Each professional's ZIP Code was matched to counties per the US Postal Service ZIP Code Crosswalk Files. The total number and density of physician and advanced practice professionals per 100,000 residents were calculated per county nationwide. Counties were categorized as urban (large central metropolitan, large fringe metropolitan, medium metropolitan, and small metropolitan) or rural (micropolitan and noncore) using the National Center for Health Statistics Urban-Rural Classification Scheme. Comparisons between rural and urban county caregivers were conducted with the chi-square test and odds ratios. Population densities were compared with the Wilcoxon rank sum test. A bivariate density map was made to visualize the nationwide distribution of orthopaedic caregivers and determine the percentage of rural counties with no orthopaedic caregivers as well as whether orthopaedic advanced practice professionals practiced in counties not containing any surgeons. Additionally, to compare states with NP's full versus restricted practice authority, each NP was grouped based on their state to determine whether NPs in states with full practice authority were more likely to practice in rural counties. We identified a group of 31,091 orthopaedic caregivers, which was comprised of 23,728 physicians, 964 NPs, and 6399 PAs (7363 advanced practice professionals). A total of 88% (20,879 of 23,728) of physicians and 87% (6427 of 7363) of advanced practice professionals were in urban counties, which is comparable to nationwide population distributions. A total of 39% (1237 of 3139) of counties had no orthopaedic professionals (defined as orthopaedic surgeons or advanced practice professionals) in 2019. Among these counties, 82% (1015 of 1237) were rural and 18% (222 of 1237) were urban. The density of advanced practice professionals providing orthopaedic services compared with the density of orthopaedic surgeons was higher in rural counties (18 ± 70 versus 8 ± 40 per 100,000 residents; p = 0.001). Additionally, 3% (57 of 1974) of rural and 1% (13 of 1165) of urban counties had at least one orthopaedic advanced practice professional, but no orthopaedic surgeons concurrently practicing in the county. There was no difference between the percentage of rural counties with an NP in states with full versus restricted practice authority for NPs (19% [157 of 823] versus 26% [36 of 141], OR 1.45 [95% CI 0.99 to 2.2]; p = 0.08). As advanced practice professionals tended to only practice in counties which contain orthopaedic surgeons, our analysis suggests that plans to increase the number of advanced practice professionals alone in rural counties may not be sufficient to fully address the demand for orthopaedic care in rural areas that currently do not have orthopaedic surgeons in practice. Rather, interventions are needed to encourage more orthopaedic surgeons to practice in rural counties in collaborative partnerships with advanced practice professionals. In turn, rural orthopaedic advanced practice professionals may serve to further extend the accessibility of these surgeons, but it remains to be determined what the total number and ratio of advanced practice professionals and surgeons is needed to serve rural counties adequately. To increase rural orthopaedic outreach, state legislatures may consider providing financial incentives to hospitals who adopt traveling clinic models, incorporating advanced practice professionals in these models as physician-extenders to further increase the coverage of orthopaedic care. Furthermore, the creation of more widespread financial incentives and programs aimed at expanding the experience of trainees in serving rural populations are longer-term investments to foster interest and retention of orthopaedic caregivers in rural settings.

Land-use reforms and housing costs: Does allowing for increased density lead to greater affordability?

We generate the first cross-city panel dataset of land-use reforms that increase or decrease allowed housing density and estimate their association with changes in housing supply and rents. To generate reform data, we use machine-learning algorithms to search US newspaper articles between 2000 and 2019, then manually code them to increase accuracy. We merge these data with US Postal Service information on per-city counts of addresses and Census data on demographics, rents, and units affordable to households of different incomes. We then estimate a fixed-effects model with city specific time trends to examine the relationships between land-use reforms and the supply and price of rental housing. We find that reforms that loosen restrictions are associated with a statistically significant 0.8% increase in housing supply within three to nine years of reform passage, accounting for new and existing stock. This increase occurs predominantly for units at the higher end of the rent price distribution; we find no statistically significant evidence that additional lower-cost units became available or moderated in cost in the years following reforms. However, impacts are positive across the affordability spectrum and we cannot rule out that impacts are equivalent across different income segments. Conversely, reforms that increase land-use restrictions and lower allowed densities are associated with increased median rents and a reduction in units affordable to middle-income renters.

Abstract Number ‐ 264: Examining The Impact Of Area Deprivation On Patient Outcomes In LVO AIS

Introduction The Area Deprivation Index (ADI) is a validated neighborhood‐level measure that utilizes variables such as income, education, and employment to quantify relative socioeconomic disadvantages. Here we explore the impact of disparities on EVT access. Methods From our prospectively maintained multi‐hospital registry, we identified patients with LVO AIS from January 2019‐ June 2020. Patient addresses and zip‐codes were validated using US Postal Service codes and matched to census‐tract level ADI scores that were obtained from Neighborhood Atlas. ADI were categorized into high and low using the median ADI as the cuto!. The primary outcome was utilization of EVT and IV tPA and was determined using multivariable logistic regression and expressed as OR [95% CI]. All p‐values are two‐sided with p < 0.05 defined as statistically significant. All analyses were conducted using RStudio (Version 1.2.5001). Results Among 637 patients with LVO AIS, median age was 68, 46% were female, 53% were white, 27% were black, and 78% identified as Hispanic. Median state ADI was 5 IQR [5]. NIHSS was similar between low/high ADI (mean(SD): 13.3(7.75) vs 13.6(8.62), p‐value 0.69) regions. ADI was significantly associated with race (6.41 vs 4, black vs. white, p‐value 0.03). In the univariable analysis, patients treated with EVT had lower mean ADIs (5.2 vs. 4.6, no EVT vs. EVT, p< 0.02). In multivariable analysis adjusted for age, sex, race, ethnicity and NIHSS, higher ADI was significantly associated with greater rates of IV tPA usage (OR 1.7 [1.01‐ 2.98]) but not EVT usage (OR 0.63 [0.04‐1.0]) Conclusions Patients residing in disadvantaged neighborhoods may have reduced rates of reperfusion therapy, despite comparable acute stroke presentation symptoms. These findings are consistent with prior studies demonstrating poorer health outcomes in these populations.

Abstract TMP89: Examining The Impact Of Area Deprivation On Patient Outcomes In LVO AIS

Intro & Background: The Area Deprivation Index (ADI) is a validated neighborhood-level measure that utilizes variables such as income, education, and employment to quantify relative socioeconomic disadvantages. Here we explore the impact of disparities on EVT access. Methods & Materials: From our prospectively maintained multi-hospital registry, we identified patients with LVO AIS from January 2019- June 2020. Patient addresses and zip-codes were validated using US Postal Service codes and matched to census-tract level ADI scores that were obtained from Neighborhood Atlas. ADI were categorized into high and low using the median ADI as the cutoff. The primary outcome was utilization of EVT and IV tPA and was determined using multivariable logistic regression and expressed as OR [95% CI]. All p-values are two-sided with p<0.05 defined as statistically significant. All analyses were conducted using RStudio (Version 1·2·5001). Results: Among 637 patients with LVO AIS, median age was 68, 46% were female, 53% were white, 27% were black, and 78% identified as Hispanic. Median state ADI was 5 IQR [5]. NIHSS was similar between low/high ADI (mean(SD): 13.3(7.75) vs 13.6(8.62), p-value 0.69) regions. ADI was significantly associated with race (6.41 vs 4, black vs. white, p-value 0.03). In the univariable analysis, patients treated with EVT had lower mean ADIs (5.2 vs. 4.6, no EVT vs. EVT, p<0.02). In multivariable analysis adjusted for age, sex, race, ethnicity and NIHSS, higher ADI was significantly associated with greater rates of IV tPA usage (OR 1.7 [1.01-2.98]) but not EVT usage (OR 0.63 [0.04-1.0]) Conclusion: Patients residing in disadvantaged neighborhoods may have reduced rates of reperfusion therapy, despite comparable acute stroke presentation symptoms. These findings are consistent with prior studies demonstrating poorer health outcomes in these populations.

Bell Labs and the ‘neural’ network, 1986–1996

AbstractBetween 1986 and 1996 researchers at the AT&T Bell Laboratories Adaptive Systems Research Department curated thousands of images of handwritten digits assembled by the United States Postal Service to train and evaluate artificial neural networks. In academic papers and conference literature, and in conversations with the press, Bell Labs researchers, executives and company spokespeople deployed the language of neurophysiology to position the systems as capable of codifying and reproducing feats of perception. Interpretations such as these were pivotal to the formation of brain–computer imaginaries that surrounded the development of the systems, which obscured the institutional infrastructures, clerical and cognitive labour, and the manipulation and maintenance of data on which feats of ‘recognition’ depended. Central to building the group's networks was the development of data sets constructed in consort with the US Postal Service, which arbitrated between the practicality of conducting research and the representation of an extensive catalogue of possible forms and permutations of handwritten digits. These imaginaries, which stressed a likeness with the human brain, were compounded by the promotion of ‘successful applications’ that took place under the AT&T corporate umbrella and with the essential support of US Postal Service workers to correct system errors.

Geospatial analysis of patients' social determinants of health for health systems science and disparity research.

Geospatial analysis of patients' social determinants of health for health systems science and disparity research.

US Postal Service announces rate hike for holiday season

The United States Postal Service has announced a temporary price hike for key package products for the 2022 peak holiday season. The rate adjustment is similar to ones in past years meant to help cover extra handling costs to ensure a successful peak season, the agency said. Its impacts on philanthropic organizations, will vary, but will be especially significant for nonprofits that use the USPS to ship items from website sales and/or mail larger swag for donors as part of year‐end fundraising campaigns. Those that don't ship anything during the holiday season won't be impacted, as the general nonprofit rate will be unchanged.

The impact of extreme heat on workplace harassment and discrimination

I study the impact of extreme heat on the incidence of harassment and discrimination using data on Equal Employment Opportunity (EEO) charges brought forward by US Postal Service (USPS) workers. I analyze more than 800,000 EEO charges filed between FYs 2004 and 2019. I find that heat stress experienced on days when maximum temperatures exceed 90 °F increases EEO incidents by roughly 5% relative to days when temperatures are between 60 °F and 70 °F. The uncovered effect is widespread across the USPS and appears to be driven by changes in the number of incidents rather than in their reporting.

‘Some Time We Have Trouble in Getting Mail. And Everything Else Here’: Black Women, Freedom Food and the US Postal System

ABSTRACTThis article puts food at the centre of the Civil Rights Movement by illuminating rural Black women's experiences accessing food and survival goods in Mississippi from 1964 to 1968. Examining letter correspondence, it demonstrates how Black women strategically participated in the little‐known postal benevolence programme, ‘Box Project’, to feed their families. Within the context of surplus commodities and the food stamp programme, the article reveals how the postal system allowed Black women to acquire food and engage in conversations with northern sympathisers about the insidious state welfare structure under which they lived. As the volume of boxes and letters entering Mississippi increased, so did the risk of Black women's strategic use of the interstate mail services. The US Postal System, as quotidian and seemingly benign a state apparatus, was a battleground for food and freedom for ordinary rural Black women.

Use of Complementary and Integrative Medicine Among Patients With Glioblastoma Multiforme Seen at a Tertiary Care Center.

BackgroundGlioblastoma multiforme (GBM) is among the most aggressive and lethal tumors, with a median survival of 12–15 months. Many patients use complementary and integrative medicine (CIM) therapies to supplement their cancer treatment.ObjectiveTo determine the prevalence of CIM use and identify the most frequently used types of CIM in a cohort of patients with GBM seen at a tertiary care medical center in the United States.MethodsAn anonymous survey was mailed through the US Postal Service from August 1, 2019, through February 21, 2020, to patients with GBM.ResultsA total of 346 surveys were mailed, and 146 responses (42%) were received. The median age of respondents was 61 years (range, 52–68 years), and 85 (58%) were male. Most patients had undergone surgery (90%), chemotherapy (96%), and radiotherapy (95%). The median time from diagnosis of GBM to survey participation was 18 months (range, 12–31 months). Most respondents (81%) used some form of CIM, most frequently meditation (22%), relaxation and other stress management techniques (19%), chiropractic therapy (16%), and acupuncture (12%). Compared with men, women more commonly meditated (32% vs 16%; P = .046) and practiced yoga (20% vs 6%; P = .04). We observed age-based differences, with younger patients more commonly meditating, practicing relaxation and stress management techniques, and receiving chiropractic therapy (P < .05 for all).ConclusionsProviders should encourage patients with GBM to discuss their interest in CIM therapies and guide them to evidence-based treatments that may help improve their quality of life.

Using postal change-of-address data to predict second waves in infections near pandemic epicentres.

We propose that postal Change-of-Address (CoA) data can be used to monitor/predict likely second wave caseloads in viral infections around urban epicentres. To illustrate the idea, we focus on the tri-state area consisting of New York City (NYC) and surrounding counties in New York, New Jersey and Connecticut States. NYC was an early epicentre of the coronavirus disease 2019 (Covid-19) pandemic, with a first peak in daily cases in early April 2020, followed by the second peak in May/June 2020. Using CoA data from the US Postal Service (USPS), we show that, despite a quarantine mandate, there was a large net movement of households from NYC to surrounding counties in the period April-June 2020. This net outward migration of households was strongly correlated with both the timing and the number of cases in the second peaks in Covid-19 cases in the surrounding counties. The timing of the second peak was also correlated with the distance of the county from NYC, suggesting that this was a directed flow and not random diffusion. Our analysis shows that CoA data is a useful method in tracking the spread of an infectious pandemic agent from urban epicentres.