Race-specific time trends in Autism Spectrum Disorder prevalence are tracked among 3-5 year-olds and 8 year-olds identified by the U.S. Individuals with Disabilities Education Act (IDEA) and the Autism and Developmental Disabilities Monitoring (ADDM) Network, respectively. White ASD prevalence historically has been higher than other racial groups but plateaued for IDEA birth cohorts from ~ 2004 to 2007 before resuming its increase. Black and Hispanic IDEA prevalence increased continuously and caught up to whites by birth year ~ 2008 and ~ 2013, respectively, with black prevalence subsequently exceeding white prevalence in the majority of states. Plateaus in white prevalence occurred in some ADDM states for birth years 2002-2006, but IDEA trends suggest prevalence will increase across all racial groups in ADDM's birth year 2008 report.