On December 31, 2015, state and federal prisons combined held a total of 1,476,847 people, of whom 499,400 were non-Latinx whites, 523,000 were non-Latinx blacks, 319,400 Latinx, and 135,100 whose race/ethnicity was counted as "other".

Click here for complete datatable of Number of People in the US Serving Time in State and Federal Prisons, by age, sex, race, and Latinx ethnicity, on December 31, 2015

Source

Carson, E. Ann, and Mulako-Wangota, Joseph. Bureau of Justice Statistics. Estimated sentenced state and federal prisoners per 100,000 U.S. residents, by sex, race, Hispanic origin, and age, December 31, 2015. Generated using the Corrections Statistical Analysis Tool (CSAT) - Prisoners at www.bjs.gov on December 31, 2016.