The mental health crisis lifeline 988 will begin operating July 16, 2022. In the absence of appropriately trained first responders, including crisis intervention teams (CITs), persons experiencing behavioral health crises face the risk of incarceration and even death. To assess county-level access to CIT in 2015 and 2020 and its association with area characteristics and state policies in 2020. This cross-sectional study included 10 430 facilities from the 2015 National Directory of Mental Health Treatment Facilities and 10 591 facilities from the 2020 National Directory of Mental Health Treatment Facilities, attributed to 3142 US counties. Area measures included need (suicide, drug-related overdose mortality), rurality, and demographic characteristics. State-level policies included 5 Medicaid policies enacted prior to 2020 and 2 recent policies intended to assist implementation of the 988 lifeline. Whether there was at least 1 facility that reported offering a CIT that handled acute mental health issues at the facility or off-site for each county in 2015 and, separately, in 2020. Most US residents (88%) resided in a county with at least 1 facility offering CIT, although half of US counties had no facility offering CIT (2015: 1537 of 3142 [49%]; 2020: 1512 [48%]). Almost 1 in 5 counties, representing 9% of the population, experienced a change in county-level access from 2015 to 2020. Unadjusted analyses indicated residents of counties without vs with CIT access were more likely to be older and uninsured (top quartile of percentage of residents aged >55 years: 502 of 1512 [33%] vs 283 of 1630 [17%]; P < .001; top quartile of percentage of residents uninsured: 500 [33%] vs 285 [17%]; P < .001) and were more likely be rural (frontier: 500 [33%] vs 144 [9%]; P < .001). Similar results, excluding counties in the top quartile of residents aged older than 55 years, were found in adjusted analyses. Counties without vs with CIT access were less likely to be in states that expanded Medicaid (788 [52%] vs 1102 [68%]; P = .01) and in states that allow Medicaid to pay for short-term stays in psychiatric hospitals (34 [2%] vs 73 [4%]; P = .02). Other Medicaid-related associations were not statistically significant in adjusted analyses. In this study, most US residents lived in counties with access to at least 1 CIT, but fewer than half of US counties had such access. Policies to encourage facilities in rural counties to offer CIT may help realize the potential of the new lifeline.