A once-great rail hub nears the end of the line : Capital area growth and changes in freight routes combine to doom a 20th-Century landmark.

For more than 70 years, the rail yard in this town where George Washington often slept and Robert E. Lee once lived was one of the busiest and largest east of the Mississippi, a hub for hundreds of freight trains operating on the north-south corridor.

The Potomac Yard, six miles long and nearly half a mile wide, handled 6,000 freight cars a day in the 1940s and had 1,600 people on the payroll. On its 125 miles of track, cars were taken off incoming trains and “humped” down a gentle incline to make up new trains headed for Bangor, Me., Jacksonville, Fla., and a hundred places in between.

But today, the Potomac Yard--known as the “Gateway to the South”--is passing into railroading history as crews tear up the tracks, stack the wooden ties for sale and watch the payroll dwindle to 45 people. Though still used by 1,600 freight cars a day, the yard is being “downsized,” railroad lingo for being issued a death warrant.

The reason: Its 526 acres are more valuable as commercial and residential real estate than as a place to move trains around.

“As a railroad man, this yard is full of nostalgia,” said Jack McGinley, yard superintendent for the Richmond, Fredericksburg & Potomac Railroad Co. (RFP). “But as a businessman, I know nostalgia doesn’t provide paychecks.”

The yard is a victim of changes in the railroad industry and of the rapid growth of the Washington, D.C., area. Alexandria, just across the Potomac River from the nation’s capital, in the past two decades has been transformed from a deteriorating Southern town into a gentrified community of trendy restaurants and half-million-dollar homes.

Amid much controversy, RFP wants to develop about 320 acres of Potomac Yard into a commercial and residential satellite community for 40,000 people. The plan, known as Alexandria 20/20, has yet to be approved by the Alexandria City Council and is meeting opposition from groups such as No Gridlock, which advocates cautious development for affluent Alexandria.

Opponents of the proposal point with disdain to a nearby development on railroad land, a place known as Crystal City, as precisely the kind of project that would change the character of Alexandria.

Whatever shape Alexandria 20/20 eventually takes, Potomac Yard is doomed. Within a few years, the 50 tracks will be reduced to six for trains roaring through Alexandria’s outskirts at high speed. The staff at Potomac will be reduced to no more than 20 people, and the assembly of trains feeding in from different lines will be handled at Florence, S. C., Rocky Mount, N. C., and other yards.

The switching of tracks to keep trains on certain routes, once done by hand here, already has been transferred to computer operators in RFP’s Richmond, Va., headquarters, 110 miles away.

“If you’ve got railroading in your blood, all this is very disheartening,” yard assistant superintendent Irv Barksdale said.

The two-story brick bunkhouse has long been abandoned and the two control towers--one for northbound traffic, one for southbound--stand unused. The roundhouse is in disrepair and nothing remains of the icehouse that once provided refrigeration for Florida produce headed for the Northeast.

Even before the development plan, Potomac Yard had been losing its importance for many reasons: The interstate highways system and the decline of the Northeast’s smokestack industries had reduced the volume of north-south rail traffic; mergers of railroad companies resulted in some rerouting through Hagerstown, Md., and a wreck near Baltimore involving a freight train and an Amtrak train in 1987 led Congress to pass legislation requiring that freight tonnage on the passenger-laden Washington-to-New York City corridor be reduced.

“It was a pleasure to come out here and get to work every day,” said Carl Rose, one of the two engineers left at Potomac Yard. “There were so many trains coming in and out, 24 hours a day, that you hardly had time to catch your breath.

“If anyone had told us five or six years ago that this was going to happen, we wouldn’t have believed him.”