The information re: Census reporting in that article is misleading. Self-reported race identification in national census began in 1970 and is tied to administration of federal civil rights legislation (Title VII and Voting Rights Act) and new agencies, e.g. HUD, which did not exist in the prior census, 1960. Prior to that state statiticians estimated race distributions (for supplemental political publications) from county-level data, collected by government employees and NGOs. The salient feature of that methodology was racist hygeine, such that local magistrates were able to determined and enforce class/caste regimens, regardless of phenotypical ambiguities ("passing") of any one household.

Here are historical Census tables. The note to PE-11-1900 (.xls) qualifies the data sets thus:

The worksheets for 1900-1929 represent the resident population of the United States, by single year of age (0 to 75+), race (White, Nonwhite), and sex.  Data for these years exclude the Armed Forces overseas and the population residing in Alaska and Hawaii.  Unrounded data for these years is not available.

The worksheets for 1930-1939 represent the resident population of the United States, by single year of age (0 to 75+), race (White, Nonwhite), and sex.  Data for these years exclude the Armed Forces overseas and the population residing in Alaska and Hawaii.

The worksheets for 1940-1949 represent the resident population plus Armed Forces overseas of the United States, by single year of age (0 to 85+), race (White, Nonwhite), and sex.  Data for these years exclude the population residing in Alaska and Hawaii.

The worksheets for 1950-1959 represent the resident population plus Armed Forces overseas of the United States, by single year of age (0 to 85+), race (White, Nonwhite), and sex.  Data for these years include the population residing in Alaska and Hawaii.

The worksheets for 1960-1979 represent the resident population plus Armed Forces overseas of the United States, by single year of age (0 to 85+), race (White, Black, and Other races), and sex.
Source:  U.S. Census Bureau, Population Division; nternet Release date:  October 1, 2004

The 1990 census was the first instrument to introduce the differentiating sub-sets of race classes, e.g. "Black or African American Alone," "Black and One or more," and "Other" etc., although the granularity within class "Hispanic" remains "white" or "black." Permutations of the 5 principal "races" reported (2012e) by the next census (2010) promise that absurdity of the exercise, over all, will defy reason and application. Much less the quaint phrases "mulatto" (US) and "maroon" (Caribbean, SA).

See American Fact Finder interactive tables. Note that "White alone," "White Non-Hispanic," and "Hispanic White" are not required to report ethnic antecedents; this is the legacy of White vs Nonwhite "cultural" supremacy.

By the time I die, perhaps, 99% of Americans will have acknowledged so many "race" identities, the statistical claims of human genetic diversity will have been vindicated in real terms. Hopefully no other nation-state will adopt this institutional insanity.

My reply to Coleman earlier deliberately understates the case law surrounding the enactment of the 14th Amendment, a/k/a Equal Protection Clause, because the ideology of "race" that predicates one's (legal) humanity in the US is so profound and invidious very few residents are even capable of renouncing their intellectual and economic dependencies upon that.

For example, who will refuse to answer to "race" identification? Why bother?

Diversity is the key to economic and political evolution.