Abstract Background: Breast cancer screening (BCS) gaps have closed between non-Hispanic Black (NHB) and non-Hispanic White women when adjusted for covariates including insurance. However, gaps in breast cancer (BC) mortality persist. Washington DC and Baltimore (DC-Balt) are two high-resource cities with diverse populations, low BCS uptake, and high BC mortality. This analysis investigates the association between residence in a high NHB area and BCS uptake. Methods: This retrospective analysis used de-identified administrative data (2017–2019) from a large national US health insurer and publicly available demographic data. Included were adult (birth year 1957 to 1967) female members with a qualifying DC-Balt zip code, continuous coverage in a commercial fully insured plan, and 1+ evaluation and management (E&M) claims. Qualifying zip codes were Core Based Statistical Areas (CBSA) 47900 or 12580 per Housing and Urban Development Q1 2021 ZIP-CBSA data and zip code area type per 2019 Uniform Data System (UDS) Zip to zip code tabulation area (ZCTA) mapping. Study cohorts were created based on residence in an area of ≥40% NHB or <40% NHB. Members with a BC diagnosis were excluded. A BCS outcome was identified by presence of digital mammography or digital breast tomosynthesis claims. Population data (NHB and total) by ZCTA was from American Community Survey (ACS) Table B03002 2019 5 Yr Estimates. Multiple regression analysis included the following covariates: a specific large regional employer (SLRE), member preventive care seeking beyond an E&M visit via the proxy of lipid panel claims, and healthcare systems (HCS) variation via one-shot encoded E&M visit claim from 12 top regional HCSs. Post-hoc sensitivity analysis examined correlation of high NHB to low household income (LHI <$40k) per ACS Table B19001 and impact of LHI to regression. Results: After excluding 698 (5.0%) members with evidence of BC, 13,128 members met study criteria (22% ≥40% NHB, 78% <40% NHB). Of those, 9,161 (70%)had BCS (61% ≥40% NHB, 72% <40% NHB), 4,539 (35%) SLRE enrollment (48% ≥40% NHB, 30% <40% NHB), 11,179 lipid claims (88% ≥40% NHB, 85% <40% NHB), and 7,087 (57%) 1+ E&M visit at an identified HCS (65% ≥40% NHB, 51% <40% NHB). OR for BCS given ≥40% NHB was 0.55 (CI 0.50-0.61). Covariate OR were 0.77 (CI 0.71-0.84) for SLRE plan enrollees and 3.92 CI (CI 3.54-4.34) for lipid screening. HCS E&M exposure OR were significant (p<0.05) at 9 of 12 HCS. 7 HCS had higher OR and 2 lower OR. HCS OR ranged from 1.98 (CI 1.61-2.45) to 0.56 (CI 0.45-0.71). LHI was correlated with NHB ≥40% (r=0.29), but not significant in regression. LHI did not change significance or magnitude of NHB ≥40% or other covariates. Conclusion: Despite the Affordable Care Act’s mandate that most insured patients pay nothing out of pocket for BCS, insured women living in areas of Washington DC and Baltimore having higher minority populations are less likely to be screened than insured women living in lower minority population areas. This analysis suggests community-based outreach needs to target all women living in high minority population areas as disparities exist even among women with insurance. Multiple stakeholders (e.g. government, employers, healthcare providers, insurers, community support services) need to collaborate to reduce remaining barriers to BCS and actively facilitate this high value preventive care. Table 1.Cohort CharacteristicsNot Screened (N=3967) (30.2%)Screened (N=9161) (69.8%)Overall (N=13128)ZCTA NHB Pct0-20%2247 (56.6%)5983 (65.3%)8230 (62.7%)>20-40%622 (15.7%)1501 (16.4%)2123 (16.2%)>40-60%314 (7.9%)577 (6.3%)891 (6.8%)>60-80%400 (10.1%)528 (5.8%)928 (7.1%)>80-100%384 (9.7%)572 (6.2%)956 (7.3%)ZCTA LHI<$40k Pct0-20%2684 (67.7%)6490 (70.8%)9174 (69.9%)>20-40%1153 (29.1%)2399 (26.2%)3552 (27.1%)>40-80%130 (3.3%)272 (3.0%)402 (3.1%)Lipid ClaimNo1098 (27.7%)851 (9.3%)1949 (14.8%)Yes2869 (72.3%)8310 (90.7%)11179 (85.2%)SLRENo2432 (61.3%)6157 (67.2%)8589 (65.4%)Yes1535 (38.7%)3004 (32.8%)4539 (34.6%)Any 12 HCSsNo1972 (49.7%)4069 (44.4%)6041 (46.0%)Yes1995 (50.3%)5092 (55.6%)7087 (54.0%) Citation Format: James Staib, Kierstin Catlett, Stacey Dacosta Byfield. Breast cancer screening disparities among insured women in the Washington DC-Baltimore area [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-14-07.