County fairs in Fairfax, which date back to 1752 and were officially recognized in the Virginia Constitution of 1870, have had their ups and downs through time, even disappearing between the 1950s and the 1970s.

But in recent years, the fair has grown in size, with more visitors, crafts, rides and entertainment. Tomorrow evening, the county will kick off the annual summer event. Close to 100,000 people are expected to pass through turnstiles on the George Mason University campus, site of the fair since 1982.

This year, visitors will experience expanded exhibits and rides at the three-day event.

The showpiece of this year's fair is the new Arts and Sciences Center, which offers 19 free hands-on exhibits that let children experiment and create while learning. Through activities, they can learn about magnetic force, electrical current, space science, color mixing and Japanese fish painting, among other things.

The center is sponsored in part by several area high-technology companies, the county school system and local arts organizations. "It really offers kids a chance to learn and have fun at the same time," said fair organizer Lynne Caswell.

Children will enjoy again this year the Children's Avenue, which includes small games, pony rides, a soccer kick and a petting zoo.

Bingo also has been added this year. Games will be played throughout the three-day event, offering cash prizes. Proceeds will be divided among county nonprofit organizations and the fair.

Fair rides and games have been expanded to 35 this year and the arts and crafts show area has been enlarged to include more than 130 booths. The show includes artists from Northern Virginia and nine other states.

Always popular with fair-goers is the wide variety of live entertainment. Again this year, national and locally recognized groups will perform on the fair's three stages.

Featured groups include Blood, Sweat and Tears, the Forester Sisters, the Seldom Scene, Riders in the Sky, Bill Haley's Comets and many others. "We realized last year how much people enjoyed the different groups, so this year we expanded to include more," Caswell said.

The Children's Stage will feature entertainment geared toward the younger crowd.

Other highlights of the weekend include the Virginia State Championship Chili and Barbecue Cook-Off, a trade fair, a health awareness area and historical exhibits.

Fair tickets are $5 for adults and $2 for children on Saturday and Sunday. Adult tickets for Friday night are $3, children $2.