Washington ? America really is a country on the move. In the last five years of the 20th century, close to half the population packed up and moved to different homes.

Usually, the moving van didn’t have to travel too far — nearly one-quarter of the country’s 262.4 million people 5 and older moved to a new address in the same county, according to a Census Bureau report released Tuesday.

The South attracted the most transplants — 1.8 million more moved into the region — while the West stayed about even, and the Northeast and Midwest saw declines.

Nevada, the fastest-growing state during the 1990s, had the highest percentage of movers — 63 percent — followed by Colorado and Arizona, both at 56 percent. About one-quarter of Nevada’s population moved in from another state between 1995 and 2000.

The study, culled from responses to the 2000 head count, didn’t include an age breakdown or a look at why people moved, only if they did and where they did.

But typically, the type of move depends on a person’s age, said John Logan, sociologist at the State University of New York at Albany. Long-distance moves are most common among people from their late teens to early 30s, primarily for college or a better job, he said.

“Long-distance moves have generally been about making a significant change in your life and hoping to build a better future, and that has been especially the case for young adults who are free to do that,” he said.

People in their mid-30s through 50s with children tend to make more shorter moves in search of a bigger home or quieter neighborhood, he noted, while those in their 60s and older move to warm-weather climates or closer to family members after retirement.

Almost half have moved

Overall, 45.9 percent of the 262.4 million U.S. residents age 5 and older in 2000 had moved in the previous five years, according to the Census Bureau. That figure includes 7.5 million people who moved to America from abroad.

The five-year moving rate has hovered near 46 percent since 1970.

Warm-weather destinations in the South and West that were unattractive decades ago are now more livable because of technology and upgraded infrastructure systems, said Robert Lang, a demographer at the Metropolitan Institute at Virginia Tech in Alexandria, Va.

“Air conditioning and the interstate highway system defeated the remoteness of these places,” Lang said.

Such states have also become popular retirement destinations, said the bureau’s Carol Faber, an author of the report.

College draw

Communities near military bases and college towns have the highest proportion of movers, led by the Jacksonville, N.C., metropolitan area at 46 percent. That area includes the Camp Lejeune Marine base. It was followed by Bryan-College Station, Texas, which includes Texas A&M University, and Lawrence, Kan., home to Kansas University.

Only 21 percent of Nevada residents were born there, the lowest percentage in the country, followed by Florida and Arizona, popular destinations for retirees and new immigrants.

States in the Midwest, mid-Atlantic and Deep South had the highest proportion of people living in the state in which they were born, which includes people who moved away and then returned.

Louisiana had the highest percentage of residents who are natives, with nearly 80 percent, followed by Pennsylvania and Michigan.

In Louisiana, many among the state’s large Cajun population don’t leave because they live on land owned by families for generations, and because of strong family ties, said Jacques Henry, a University of Louisiana-Lafayette sociologist.