Here's how the Washington & Old Dominion railroad created Northern Virginia's suburbs – Greater Greater Washington
Today, the Washington & Old Dominion (W&OD) is a paved trail used for fun and commuting across Northern Virginia. Of course, originally the Washington & Old Dominion was a railroad — one with a long and convoluted history that helped form Dunn Loring, Reston, Herndon, Sterling, Ashburn, and other communities that still exist to this day.
Source: ggwash.org