Love it or hate it, the Metro is the heartbeat of D.C. and one of the busiest public transportation systems in the country. But, before we had a Metro, all we had was … traffic. Lots of it.
That’s why in 1944 engineering firm, J.E. Greiner Company, proposed a seven-mile streetcar subway system that would have been twice as long as any in the U.S. It was to have three lines: one similar to the Red line, another parallel to the Orange/Blue/Yellow lines, and a third on 14th St., from Thomas Circle to downtown.
The system was designed to be top notch. N trains would share tracks, many of the stations would get mezzanines with elevators, and platforms could accommodate up to six cars. The whole thing would have cost $56M ($800M today) in taxpayer dollars.

The proposed streetcar routes through D.C. using a three-tunnel streetcar subway system. (District Department of Transportation, “Streetcar Subways,” DDOT Historic Collections)
Unfortunately, this proposal was significantly pared down a few years later because of cost concerns and complaints that it would require too many transfers. A new, shorter, more complex version was set to be built in 1950, but was killed by the Capital Transit who thought that subways were “too rigid” to adjust service for changing conditions.
D.C. chugged along with its appalling traffic and classic cabs for another 17 years. Finally, the original five Metro lines were built and opened to the public, starting with the Red line.