Overall U.S. prevalence percentages provided in the research that has been sponsored by the government through the CDC agency across Race/ethnicity demographics are linked and quoted below.
Access and affordability for diagnosis plays a role, as well as awareness and cultural differences.
The statistics for Black, non-Hispanics are close to that of White, non-Hispanics. However, there are some states in the linked research quoted below where Black, non-Hispanics have a higher prevalence rate than White, non-Hispanics. And while overall, Hispanics have the lowest prevalence rates measured in the US, there is close to double the prevalence measured among Hispanics, in Florida, where Dade county was the chosen data collection county.
If the opportunity for diagnosis was equally accessed across ethnic groups it is possible that White, non-Hispanics, could be 3rd among the most diagnosed Race/ethnicity groups if the increasing prevalence rates among Black non Hispanics, and Hispanics are an indication of eventual prevalence statistics among the different Race/ethnicity groups.
This is the same nation-wide government sponsored report/study where the 1 in 88 statistic comes from.
http://www.cdc.gov/ncbddd/autism/documents/ADDM-2012-Community-Report.pdf
Quote:
Overall prevalence of ASDs: 11.3 per 1,000 (or 1 in "88")
Range of prevalence estimates across sites: 4.8 per 1,000
to 21.2 per 1,000
Boys: 18.4 per 1,000 (or 1 in 54)
Girls: 4.0 per 1,000 (or 1 in 252)
Race/ Ethnicity
White, non-Hispanic: 12 per 1,000
Black, non-Hispanic: 10.2 per 1,000
Hispanic: 7.9 per 1,000
Asian or Pacific Islander: 9.7 per 1,000
Quote:
The largest increases in prevalence over time were among
Hispanic and black children
White, non-Hispanic children: 70% increase
Black, non-Hispanic children: 91% increase
Hispanic children: 110% increase