DC has its problems, but we (mostly) dodged a bullet by heading off the interstate planners, who would have destroyed downtown and Capitol Hill. They would have sliced the city into small segments moated by arterial roads. The most famous avoided monstrosity was the proposal to turn the C&O Canal into another expressway like the George Washington Parkway on the Virginia side.
The 1960's and LBJ's Great Society got almost everything wrong, and we are still digging out of the wreckage.