In the 20s and 30s, the DC area held its own in quality golf. Ross's original Indian Spring was legendary; along Conn Ave was Kirkside, Chevy Chase and then Columbia; Flynn's Town and Country was about a mile away; Flynn's PGCC and Manor were high quality; Bannockburn may have been one of the most interesting given the severe topography; and in the 1920s, the US Publinx was held at East Potomac; and of course, Congressional, Burning Tree, and a more expansive Kenwood. Golfers must have thought the Potomac was a barrier. Why else would only 3 courses have been built in VA - Army-Navy, Washington G&CC, and Belle Haven? Anyway, real estate development affected many of these courses and it's arguable that what's been built since doesn't measure up in quality.
Paul,
I don't think real estate was the reason for the closure of the original PGCC. The clubhouse is still there and most of the land that held Flynn's holes is still open. A couple of Flynn's greens still can be seen. I think the changing character of the neighborhood is what did it in.
Chip
If you've seen a course that covered both sides of River Road, it was probably Kenwood. The 9 holes on the south side of River Road were built over with real estate and the 9 on the north were supplemented by a couple holes on the same property and the rest on new land across Goldsboro Rd. The current course is far more compact than the original.