Hispanics were counted as whites in 1940, but for the first time ever, the U.S. made an attempt to measure the size of the Hispanic population that year. The U.S. resumed enumerating its Hispanic/Latino population in 1970, with Hispanics being enumerated in every U.S. census since then. The U.S. Census Bureau also began offering Hispanics several sub-group options from which they could identify themselves, such as Mexican, Puerto Rican, Cuban, et cetera (these Hispanic sub-group options have changed over time). The Other race category was added in 1950, and in 2000 multi-race responses were tabulated for the first time (instructions now explicitly inform respondents that they can choose multiple race boxes). Because multiracial respondents are now allowed, U.S. Census data since 2000 is not directly comparable with that of previous censuses. While people nowadays are enumerated by race based on self-identification, until 1950 their race on the census was mainly determined by their census enumerator. During this time multiracial people who were White and of another race were usually marked down as belonging to the other race due to the One drop rule. The instructions provided to enumerators endorsed this practice.
