There's a law still on the books in Virginia," says Albert Nicely, "that if a man's driving a motor vehicle and he meets a horse on the road, he has to stop. And if his vehicle is bright colored, he has to cover it with a sheet so as not to scare the animal. Then he has to help lead the horse past the vehicle."

Nicely is a man who keeps up with horse-power trivia. As the organizer of the reunion of the 1976 Bicentennial Wagon Train, it is his job to see that the about 60 participants have a safe month-long journey from Nicely's hometown of Goshen, Va., to Valley Forge, Pa. By mid-June he had brought the train, unharmed and on schedule, to northern Loudoun County.

The reunion train's participants are from across the country and are of every age, from a 5-week-old infant to several members who are old enough to be grandparents and great-grandparents.

"We're 'Little House on the Prairie,' " Nicely likes to tell visitors. "There are other groups that are 'Dallas,' but we don't do any of that stuff. We're a nice family group."

On the road, "outriders" carry orange fluorescent flags to direct cars, trucks and the horse-drawn wagons. For the most part, the train has moved peacefully along. Oh, there was the amazed truck driver who locked the brakes of his 18-wheeler when the wagon train came into view. The screeching tires startled some of the less-seasoned horses and mules, causing them to "put on a show," but it didn't take long to get things moving again.

Along the way, onlookers rarely have failed to give the wagon train a friendly welcome. Just before the Virginia-West Virginia line, a man and a little boy passed a watermelon to the lead wagon.

Many wagons in the reunion train are among the 19th century's best, manufactured by Brown Mitchell and Studebaker, the same Studebaker that later turned to making automobiles.

Cecil Marshall, from Ohio, says you can tell the age of a wagon by the wormholes in the poplar planks of the wagon's freight beds. "The worms won't bother with a piece of yellow poplar until it's at least 100 years old," he explains, pointing with pride at the tunnels and tiny holes in his own carefully restored Mitchell wagon.

But as proud as the owners are of their antique wagons, they are not purists when it comes to 20th versus 19th century comforts. They opt for the 20th century almost every time.

"We started out allowing people to sleep only in their wagons or under them and to use only wooden wheels," says Texan Clyde Todd, "but that didn't last long." The mule-drawn wagon Todd and his wife Doyce own sports rubber wheels (for a smoother ride), red bucket seats from a car instead of the traditional "buckboard," and a tape deck.

At the end of the day, the Todds abandon the wagon to cook and to sleep in the vinyl comfort of their camper, which every morning is shuttled about 20 miles ahead to the next campsite along with the train's supply trucks, water truck and "potty" wagon.

The Todds' friends Dorothy and Fred Denmark rode with 10 wagon trains last year but have yet to leave the comfort of their roomy camper. They don't even own a horse or wagon, but they enjoy the friends they make on the wagon trains and the excitement of the trips.

Still, it's a sentimental journey into the past for most of the travelers. As a child, Clyde Todd watched longingly as his father loaded up the family buckboard with handmade furniture, which he sold throughout Texas.

In 1961, as a grown man, Todd heard that a wagon train was being organized to follow part of the old Shawnee Trail, a cattle trail from Texas to Missouri. He resolved to be part of it and began training two Holstein cows to harness so he could have fresh milk on the trip. When one of the cows was mistaken for a deer and killed by a hunter, Todd switched to a mule team.

The original team has been replaced by a younger one, but Todd hasn't missed a Shawnee Trail ride since his first one 21 years ago.

For Todd, his childhood dream of traveling by covered wagon has more than come true.

The Bicentennial Wagon Train is expected to arrive Saturday at Valley Forge National Historical Park, 20 miles west of Philadelphia. A special ceremony welcoming the train there has been set for 11 a.m. Saturday. Visitors are welcome at Valley Forge and the wagon train's camp, expected to be at Phoenixville, Pa., a few miles northwest of the park. Directions to the camp are available at the Valley Forge visitors' center, Rte. 363 and Rte. 23. Although visitors cannot camp at Valley Forge, park officials say numerous campgrounds and other overnight accommodations are in the area.