County Still Leads The Region In Growth Its Population Increased By 3.1 Percent Between 1990 And 1992, According To New U.s. Census Bureau Estimates.

Chester County, the fastest-growing of the suburban Philadelphia counties during the 1980s, kept up its heady pace during the early years of the 1990s.

According to U.S. Census Bureau estimates released last week, Chester County's population grew by 3.1 percent between 1990 and 1992, for the highest rate in the eight-county Philadelphia area.

Stay tuned, say county officials: That rate is likely to continue throughout the decade. Those officials project that the county's population will jump by 50,000 this decade and 100,000 over the 20 years to follow.

And start planning now, warned Diane Snyder, a township supervisor in West Whiteland, or face the consequences.

By the time a community in the midst of a boom can afford good planning, ''it is usually too late," she said. "That's the tragedy of it. Our township is a prime example."

Peter Hausman, a county Planning Commission member, is worried about the prospects for orderly growth and the preservation of open space that makes the county an attractive place to live. "It is incumbent upon us to say where we are going to put these 50,000 people without destroying everything that made Chester County attractive to us," he said.

According to the new census figures, the county's population grew by an estimated 11,646 to a total of 388,042 from 1990 to 1992. Rapid development was seen in townships in the southern tier, while there was continued pressure on the center of the county, as well as gains for all of the older boroughs except Kennett Square.

While the continued high rate of growth in the 1990s has surprised some officials, the pace slowed from 1990 to 1992, according to a county tally of subdivision applications.

Chester County was among only eight counties in the state to beat the nation's growth rate of 2.5 percent for the period. Gloucester County had the second-highest growth rate in the Philadelphia area with 2.9 percent, and Bucks County was third with 2.8 percent.

Philadelphia had the only population decline in the area, with the population falling by about 33,000 people or 2.1 percent, according to the estimates. Overall growth in Pennsylvania and New Jersey was about 1 percent.