Washington, D.C. ? America’s neighborhoods took large strides toward racial integration in the last decade as blacks and whites chose to live near each other at the highest levels in a century.

Still, segregation in many parts of the U.S. persisted, with Hispanics in particular turning away from whites.

A broad range of 2009 census data released Tuesday also found a mixed economic picture, with the poverty rate swinging wildly among counties from 4 percent to more than 40 percent as the nation grappled with a housing boom and bust. Just three U.S. localities reported median household income of more than $100,000, down from seven in 2000.

Segregation among blacks and whites increased in one-fourth of the nation’s 100 largest metropolitan areas, compared to nearly one-half for Hispanics.

The latest figures reflect new generations of middle-class blacks moving to prosperous, fast-growing cities, said William H. Frey, a demographer at Brookings Institution who reviewed the census data. “In contrast, the faster national growth of Hispanics has led to increased neighborhood segregation,” Frey said.

The U.S. in many ways remains divided by race and economic lines, said John Logan, a sociologist at Brown University who has studied residential segregation.

“Whites are still on average a large majority in the places where they live, and blacks and Hispanics are the majority or near-majority in their neighborhoods,” he said. “They suggest that all the talk about a post-racial society means nothing at the level of neighborhood.”

Broken down economically, in 21 counties more than 1 in 3 people lived in poverty, many of them American Indian reservations in the High Plains. Amid swirling congressional debate over taxing the wealthy, three localities in Virginia had median household income of more than $100,000 — Falls Church, and Fairfax and Loudoun counties.

The new information is among the Census Bureau’s most detailed release yet for neighborhoods, pending demographic results from the official 2010 census next spring.

Among other findings:

l New Orleans was among metros with the largest decline in segregation among blacks and whites since 2000, due largely to the exodus of low-income blacks from the city after Hurricane Katrina.

l Four New York counties — which represent four of New York City’s five major boroughs except for Manhattan — ranked at the top of longest commute times to work, all in excess of 40 minutes: Richmond (Staten Island), Queens, Kings (Brooklyn) and Bronx. Residents in King, Texas, had the quickest trip: 3.4 minutes.

l Falls Church, Va., with the highest median household income at $113,313, also had the highest share of people ages 25 and older who had a bachelor’s degree or higher. In all, 17 of the nation’s 3,221 counties had college completion rates of more than 50 percent, compared to 62 counties whose rates were less than 10 percent.

The race trends hint at the upcoming political and legal wrangling over the 2010 census figures, to be published beginning next Tuesday. The data will be used to reallocate congressional districts, drawing new political boundaries.

New Hispanic-dominated districts could emerge, particularly for elected positions at the state and local level. States are required under the Voting Rights Act to respect the interests of minority voting blocs, which tend to support Democratic candidates.

Milwaukee, Detroit and New York were among the most segregated between blacks and whites, all part of areas in the Northeast and Midwest known by some demographers as the “ghetto belt.” On the other end of the scale, cities that were least likely to be segregated included Las Vegas, Honolulu, Raleigh, N.C., and Albuquerque, N.M.