In 1960, the dissimilarity index for the United States was measured at 62.

In fact, New York's is the only one of the nation's 30 biggest school systems in which black-white segregation increased from 1968 to 2000, according to the "dissimilarity index," a measure used in the study.

Mr. Logan favors the dissimilarity index, but Gary Orfield, a professor of education at Harvard and an expert on segregation, called it "a terrible measure" in cases where the school system has few white students.

To measure segregation levels, researchers at the state university used what they call a dissimilarity index, which captures the degree to which two racial groups are evenly spread among census tracts in a city.

Karweng dissimilarity index utilizes the sum of area differences derived from a tetrahedron.

Overall, Houston has a dissimilarity index of black as compared to whites of approximately 75% according to CensusScope's segregation breakdown of the city, which is higher than the United States national dissimilarity index of 65%.

Published by the Manhattan Institute for Policy Research, the report indicates that the dissimilarity index has declined in all 85 of the nation's largest cities.

However measured by a longstanding "dissimilarity index", Metro Atlanta ranked 63rd out of 100.

Using what is called a dissimilarity index, the sociologists estimated how many blacks would have to move into a white or mixed neighborhood to create an equal balance between blacks and whites.