County-level barriers (sociodemographic barriers, limited healthcare system resources, healthcare accessibility barriers, irregular healthcare seeking behaviors, low vaccination history) may impact individuals' reasons for receiving the COVID-19 vaccine. This study linked data from REACH-US (Race-Related Experiences Associated with COVID-19 and Health in the United States), a nationally representative, online survey of 5475 adults living in the U.S (January-March 2021) to county-level barriers in the COVID-19 Vaccine Coverage Index. County-level vaccination barriers were measured using the COVID-19 Vaccine Coverage Index. Participants reported why they would or would not receive the COVID-19 vaccine in an open-ended item and their responses were coded using thematic analysis. Descriptive statistics and chi-square tests assessed whether reasons for COVID-19 vaccination intentions varied by county-level barriers and whether these distributions varied across racial/ethnic groups. Thematic analysis revealed twelve themes in participants' reasons why they would or would not receive the COVID-19 vaccine. Themes of societal responsibility (9.8% versus 7.7%), desire to return to normal (8.1% versus 4.7%), and trust in science/healthcare/government (7.7% versus 5.1%) were more frequently reported in counties with low/medium barriers (versus high/very high) (p-values < 0.05). Concerns of COVID-19 vaccine side effects/safety/development (25.3% versus 27.9%) and concerns of access/costs/availability/convenience (1.9% versus 3.6%) were less frequently reported in counties with low/medium barriers (versushigh/very high) (p-values < 0.05). Trends in the prevalence of these themes varied across racial/ethnic groups (p-values < 0.05). Future pandemic responses should consider potential ways county-level barriers shape reasons for COVID-19 vaccination.