Our work analyzes total fine particulate matter (PM2.5) and PM2.5 component concentrations over time between American Indian and non-American Indian populated counties. Between 2000 and 2018, total PM2.5 concentrations decreased less among American Indian populated compared to non-American Indian-populated counties, with significantly higher total PM2.5 concentrations found in American Indian versus non-American Indian populated counties in recent years. We observed differential trends by PM2.5 component. This study highlights disparities in PM2.5 trends between American Indian and non-American Indian populated counties over time, underscoring the need to strengthen air pollution regulations and prevention implementation on tribal lands where American Indians live.