More than two centuries after it was drawn, Mason and Dixon's much-misunderstood border is still the talk of the towns along it

You can't really walk the Mason-Dixon Line. There's the problem of creeks and rivers, including the milewide Susquehanna. And much of it is on private property -- indeed, sometimes it goes right through people's living rooms. But most of all, you can't walk the Mason-Dixon Line because it's invisible -- an arbitrary and artificial demarcation, direct and true in longitude and latitude, but without breadth or thickness.

Perhaps for these reasons, the Mason-Dixon Line is widely misunderstood. It is merely 332 miles long, and it extends only from the Atlantic Ocean to Western Pennsylvania. It is the work of two English surveyors; it was completed before the American Revolution; and it had nothing to do with the Civil War. It simply settled a boundary dispute.

But long after the border war ended, and Charles Mason and Jeremiah Dixon died, their surveying job was figuratively extended across the entire nation and became a catch phrase for a complex series of political and social issues. And to this day, nearly 2 1/2 centuries after it was drawn, the Mason-Dixon Line remains a powerful symbol that separates Yankee from Rebel, oatmeal from grits, North from South.

The metaphorical Mason-Dixon Line, celebrated in music and literature, has obscured the fact that the real Mason-Dixon Line is a stunning achievement of skill and courage. Mason and Dixon constantly fighting against accidents, hostile Indians, snow-covered mountains, flooded rivers, wild animals and nit-picking bureaucrats -- used crude instruments to plot a boundary that is still accepted by the U.S. Geodetic Survey today.

And while you can't walk the Mason-Dixon Line, you can go out and talk to the people who live on it or near it. You can follow it through many-steepled towns where people and their deeds are still connected; across fields alive with the lusty odors of earth and cattle, and over tree-tufted mountains. It is a strip of landscape, people and history.

It begins on Fenwick Island, Del., near the emerald meadows of the Atlantic, marked by a stone just outside the chain-link fence protecting the Fenwick Island Lighthouse. A woman in a velour running suit jogs by the Mason-Dixon Motel. To her left is Maryland and to her right is Delaware -- though in 1763 the state was part of the province of Pennsylvania and was called "the three lower counties."