The Prince William County Board of Supervisors last night approved the final component of a 250-acre development off I-95 that county officials and developers are already calling the Tysons Corner of Prince William County.

The project, known as the Washington Outlet Mall, is expected to bring thousands of new jobs and millions of dollars in annual tax revenues -- as well as additional traffic woes -- to the fast-developing county.

Developers of the project, Western Development Corp., have already started construction of a mall for discount stores that will be one of the largest on the East Coast. The project is slated to include more stores, offices and hotels.

Western agreed to pay for more than $5 million in road improvements to gain approval for the project, located just west of I-95, between Telegraph and Smoketown roads.

Nonetheless, county officials seemed resigned to accepting traffic headaches that planners say the project will bring to the county, despite the road improvements, in return for about 6,500 new jobs and more than $4 million in annual net fiscal benefits.

"This is a major rezoning in the life of the county," said County Executive Robert Noe. "We know we have a roads problem, but I believe that business and economic development is part of the answer, and not part of the problem."

The final piece of the project that was approved last night is a 55-acre tract straddling Opitz Boulevard. The supervisors voted 6 to 0, with one abstention, to rezone the land from agricultural to business use.

The tract, known as the Caton property, sits to the southeast of the outlet mall, centerpiece of the project, which was approved by the supervisors last winter.

The supervisors' action last night is in the context of a general commitment in Prince William to make economic development the number one priority. The county, heavily populated by commuters, wants to lure more business and commercial development, which it considers a subsidy for further residential development.

Western officials estimated that the firm's total investment in all parts of the project approaches $200 million.

They also insisted, in interviews after the board vote, that the money they are channeling toward road improvements will permit Prince William to avoid the severe traffic problems now associated with Tysons Corner, the huge commercial development adjacent to the beltway in Fairfax County.

The County Planning Commission recommended last week that the supervisors reject the Western rezoning application. Commission members said the company had not sufficiently addressed the likely traffic problems.

C. Lacey Compton Jr., attorney for Western, acknowledged that the project will create additional traffic, but argued that the county would be able to address the congestion with the new tax revenues generated by the development.

Western Development Corp. is best known in the metropolitan area as the builders of Georgetown Park, the luxury shopping mall in that fashionable Washington neighborhood.