POPULATION

Loudoun County's population, now around 70,000, is expected to double over the next 25 years. It is expected to be the fastest growing region in the Washington metropolitan area.

Most of the population growth is projected for the eastern end of the county, particularly along the Rte. 7 and Rte. 28 corridors, as young families seeking affordable housing buy their first homes.

JOBS/ECONOMIC BASE

Employment in the county, now just over 20,000, is expected, at minimum, to triple over the next 25 years, according to figures compiled by the Metropolitan Area Council of Governments. That estimate was made before Xerox announced its planned expansion last month, which could bring another 32,000 jobs to the county. Loudoun officials say more businesses in the county will mean a break in rising property taxes for residents.

LAND USE

County officials say stringent zoning laws encourage clustered development and the use of natural buffers, and prevent the kind of overdevelopment that has occurred along the Rte. 1 corridor in Fairfax.

The western portion of the county is expected to remain rural. Much of the eastern portion, where the growth is expected to center, already is zoned for industrial and office use.

TRANSPORTATION

Traffic is expected to be the No. 1 problem generated by the boom in development. Two roads in particular, Rte. 28 and Rte. 7, will be hit hard by the projects proposed for eastern Loudoun, officials say.

Planners say they hope to turn Rte. 28 into a four-lane limited-access highway with interchanges and to improve Rte. 7. They hope to make Rte. 643 -- now a dirt and gravel road running from Leesburg toward Dulles -- a paved highway that connects with the Dulles access road. The unanswered question: Will the state put up enough money to build the roads the county wants?