Earlier this month at a meeting of the Population Association of America, researchers presented preliminary findings that more than two million Hispanics changed their racial classification to "white" in the 2010 census from "some other race" in 2000. Overall, according to official data, 53% of Hispanics classified themselves as white in 2010.

Yet for 2020 the Census Bureau is considering racializing the constellation of Hispanic ethnicities. The current population survey asks if a person is of "Hispanic,...