James P. Allen’s research while affiliated with California State University, Northridge and other places

Residential segregation in metropolitan areas has been the subject of much research, but this article analyzes patterns of white–black and white–Hispanic segregation in counties across the United States. Our purpose was to understand county variations in this one dimension of inequality. Conceiving of segregation as relative inequality of access to neighborhood resources, we measured segregation in 2000 by the index of dissimilarity (D) calculated by blocks, mapped the index values, and correlated them with census variables. Three filters enabled us to eliminate counties with characteristics that could have corrupted the analyses, leaving us with more than 1,000 counties in each analysis. Both minority groups were less segregated from whites in the West and South and in metropolitan counties. Lower segregation was strongly associated with higher minority socioeconomic status and higher percentages of minorities living in housing built in the 1990s, and Hispanic–white segregation was lower where more Hispanics were U.S.-born or English proficient. The racial threat hypothesis was supported only weakly and inconsistently. Mapping made it possible to identify regional and local patterns of high and low segregation as well as the lower segregation of suburban counties in some large metropolitan areas.

Creating dot maps to show changes in racial and Hispanic population distributions between two census periods can be an effective way to examine one of the most important dimensions of change within any metropolitan area. Using dots of one color to show population increase and dots of a second color to show population decrease vividly reveals where changes have occurred within a larger total population. We prepared such maps for the book Changing Faces, Changing Places: Mapping Southern Californians, the text of which analyzes and interprets the population shifts evident on the maps. The maps show the expansion and contraction of racial and Hispanic populations in specific neighborhoods so that community leaders and residents alike can easily relate general trends to their localities. In this article we describe the preparation of these dot maps and explain major problems encountered in linking the 1990 and 2000 census population counts at the tract level. We explain our solutions, which we believe made possible more accurate mapping of neighborhood change.

Although residential concentrations of immigrant ethnic groups in cities were common a century ago, it is not clear to what extent members of more recently arrived groups live near each other. We attempt to determine how common such clustered settlement is today, using 2000 census data to measure concentrations of Asians, Hispanics, and their larger ethnic subgroups in fifteen large metropolitan areas. The percentage of an ethnic group that is residentially concentrated correlated significantly with the group's proportion in an area. With metropolitan areas weighted equally, 38 percent of Hispanics and 13 percent of Asians were concentrated. However, when we analyzed eight specific nationality groups, the residentially concentrated proportion ranged from 14 to 59 percent. Level of cultural assimilation appears to explain group differences in level of concentration. Although ethnic concentrations were more pronounced in the largest metropolitan areas, important concentrations were also found in many of the smaller areas in our study.

Are residents of ethnic concentrations necessarily poor? We tested this notion with Census 2000 data for Asian and Latino households in the New York, Los Angeles, and San Francisco CMSAs. Ethnic concentrations included all census tracts in which the group com- prised over 40% of the population. While many residential concentrations had low incomes, 11% of concentrated Latinos and 57% of concentrated Asians had incomes above their metropolitan medians for all households. Moreover, 18% of concentrated Asians lived in tracts with incomes at least 50% higher than the metropolitan medians. Higher-income residents within concentra- tions were more likely to be U.S.-born and proficient in English. Thus scholars need to revise the widespread view that people living in ethnic concentrations are poor. Many Asians and Latinos who can afford homes in mostly White neighborhoods prefer to live where both Whites and their Theory, historical evidence, and widely held perceptions suggest that immigrant-based ethnic residential concentrations in the United States should be found only in poor areas of cities. However, because scattered occurrences of residential clustering by higher- income immigrants and their children have been reported, scholars have begun to ques- tion the longstanding, widely held view that the economic success and acculturation of an immigrant-based ethnic group necessarily leads to the group's residential dispersal. In this study we investigate this matter directly by measuring the extent to which above- average income levels and substantial acculturation are found within ethnic residential concentrations.

Using the U.S. Census Bureau's County-to-County Migration File and Public Use Microdata Sample File, we investigated California's interstate migrants between 1995 and 2000. After mapping and discussing the spatial patterns of migrants' origin and destination counties, we calculated percentages of college graduates and detailed industries of employment for Non-His- panic White, Latino, Black, and Asian migrants. To examine migrants' social and economic fit at their destinations, we compared them to longer-term residents of both California and other leading destinations. In all cases inmigrants to California had higher percentages of college graduates than did their ethnic group in origin states, and in nearly all cases inmigrants raised the percentage of college graduates of their ethnic group in California. Migrants from California worked in destination-state industries at similar or slightly lower rates than non-migrant residents, but migrants to California were better represented in higher-status industries than longer-resident Californians.

This research compares the contemporary areal patterning of cultural and economic assimilation with patterns expected from a model of urban spatial assimilation described by Massey and modified by us. Using 1990 census data (PUMS) for 12 immigrant groups in the greater Los Angeles area, we locate the ethnic concentrations of each group and identify two additional zones based on distance from the concentration. The zones represent varying degrees of spatial assimilation. This method allows us to compare the distribution of immigrant cohorts over time and the degree of cultural and economic assimilation of residents of the different zones. Our findings confirm most geographical aspects of the modified model. Zonal differentiation occurs in the expected direction and is statistically significant although not strong for most groups. More recently arrived immigrant groups and those with higher incomes tend to show greater differences in assimilation between zones.

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 sets. 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.

How common is ethnic differentiation within census tracts and what types of tracts are most likely to exhibit this tendency? This research attempts to answer these questions with block data from the 1990 U.S. census for Los Angeles County. We measured non-random unevenness in ethnic percentage within tracts for twelve ethnic populations by means of an adjusted index of dissimilarity. Of the total of 300 sampled tracts, 48% showed statistically significant differentiation at the block level. Census tracts frequently mask details of ethnic patterning, especially in transition zones between larger ethnic settlement regiorrs. Ethnic differentiation was most clearly related to block variations in housing type and cost, and tracts with fairly uniform housing were much less likely to show significant internal differentiation. Block-level differentiation was no greater for blacks than for some Asian groups and was average or low for non-Hispanic whites and people of Mexican origin.

Using 1980 U.S. census data, we ranked all urban places over 10,000 in population according to the relative ethnic diversity of their populations, as measured by the entropy index. This statistic reflects the relative heterogeneity of the population in the areal unit, the highest values occurring when all groups are present in equal proportions. The ethnic populations were identified in terms of two different sets or groupings. The first set contains five categories: white, black, Hispanic, American Indian, and Asian and Pacific Island people. The second set has 13 categories and includes specific Hispanic and Asian ethnic groups as well as two categories of whites based on region of ancestral origin in Europe. The results show that larger cities are usually highly diverse, but the most diverse urban places are found throughout the full range of population sues. The places that ranked highest in ethnic diversity are usually part of a metropolitan area, most commonly in the Los Angeles and the San Francisco areas. A number of places in the New York City-northern New Jersey area and others in south Florida, Texas, and Hawaii also ranked high. The most ethnically diverse places are highly varied in demographic and socioeconomic characteristics, but army posts constitute a distinctive type. In contrast, the least diverse urban places tend to be small in size, suburban or nonmetropolitan, strongly white with very few minorities, and located in the Northeast and Midwest.