This could be a called a tale of two cities, but it’s a little more complicated than that.
First, you have Washington, D.C., which has had a viable heliport since early 1998, but it depends on your definition of the word “viable.”
Then you have Dallas, which has had Garland/DRW Heliport since 1988, one of fewer than a dozen stand-alone public-use heliports in the U.S. It was joined in 1994 by 49T, a heliport on the roof of the Dallas Convention Center.