Tucked along a big bend in the Potomac River, amid tidal creeks, swamps and forests, the once rural Charles County is fast becoming a booming expanse of suburbia and one of the fastest growing counties in Maryland.

Fueled by the arrival of tens of thousands of blacks, Hispanics and Asians, the county's 22 percent population increase was about the same as that of neighboring St. Mary's County, which had the state's biggest percentage increase in the past 10 years.

Charles's largest population jump came among black residents, whose numbers nearly doubled, from 31,000 to 59,000.

The county, which has seen major increases in wealth and development in recent years, is getting influxes of minorities from Prince George's County and the District as people seek better housing and schools and less crime, experts have said.

The population, which jumped from 121,000 to 147,000, saw the number of Hispanic residents jump 130 percent, from 2,700 to 6,300. The number of Asian residents doubled, from 2,200 to 4,300. The county's white population dropped about 13 percent in the past decade, from 81,000 to 71,000. Whites make up 48 percent of residents, down from 67 percent in the previous census.

In St. Mary's County, the trends were less dramatic. The population jumped from 86,200 to 105,100, according to the figures. The white population grew from 69,300 to 80,402, and the African American population grew from 11,900 to 14,800.

Whites make up 76.5 percent of the population vs. 80 percent in the previous census.

Blacks are 14 percent of residents, about the same as in the previous decade. The Hispanic population in St. Mary's grew from 2 to 4 percent of county residents. The number of Asian residents increased from 1,500 to 2,500.