Population Research and Policy Review 20: 513–533, 2001.
© 2002 Kluwer Academic Publishers. Printed in the Netherlands.
Bridging 1990 and 2000 census race data: Fractional assignment
of multiracial populations
JAMES P. ALLEN & EUGENE TURNER
California State University, Northridge
Abstract. In contrast to previous censuses, Census 2000 permitted individuals to mark more
than one race. Because the new race tables include both single-race and mixed-race categories,
measuring change during the 1990s requires some method of bridging between the two data
To accomplish this bridging, we ﬁrst identiﬁed biracial populations as of 1990 through the
race and ancestry responses of individuals in the PUMS ﬁle. With race responses assumed to
represent a person’s primary race identity, we then determined the percentage of each biracial
group that preferred each race as the primary identity. The same percentages can be used
to assign biracial persons from Census 2000 into single-race categories. We also provide
fractional assignment percentages for selected states and for the larger speciﬁc nationality
groups of mixed-race Asians.
Comparison of our 1990 estimates of the numbers in leading biracial groups with those
reported in Census 2000 suggests that our fractional assignment values are reasonable for
biracial groups other than those involving American Indians and Alaska Natives. For the latter
biracial groups and for all groups representing three or more races, we recommend equal
fractional assignment into the appropriate single-race categories.
Keywords: Census, Multiracial, Population, Race, United States
Growing mixed-race populations
The United States has long contained multiracial people – those of mixed
racial background. However, because traditional American culture holds that
people should be categorized into a series of discrete races, the multiracial
backgrounds of people have usually remained hidden (Nash 1995). The U.S.
Bureau of the Census has further diminished the public’s awareness of racial
mixing by its directions to respondents on the decennial census questionnaire.
By requiring everyone answering the race question to choose one race only,
those individuals who had more than one racial identity were forced to choose
between competing identities.
Multiracial identities have become much more signiﬁcant during the last
two or three decades because the country’s mixed-race population has grown
very rapidly. According to the Census Bureau the number of interracially