It feels impossible, and I am known for bucking up for Washington both as a city (the actual city, not the federal government I admit defines its existence) and location.
Some stuff that could help to even try to cross this impossible gap:
-Let Washington’s dream of the federal capital and not Jefferson’s vision of a mere federal campus come into play so all the below happens as fast as possible.
-Much stronger local control and government from the get-go. Congress will always be top dog but a city able to respond to its own needs as fast as possible than disinterested Congressmen from across the nation will do wonders for livability.
-Higher density zoning, skyscrapers when they come, etc. even while keeping the OTL base city plan, federal enclaves, and parks/greenery for citzenry’s and government’s sake alike.
-Get the Chesapeake and Ohio Canal rolling as fast as possible as Washington envisioned as a western gateway, perhaps THE one in TTL. It is the second best western canal site after the seemingly God-sculpted pathway of the Erie Canal.
-More (even more?) roads and rail passing through it, as big a navy yard and commercial seaport as possible, etc. to encourage merchants to come by and settle down.
-Just encouraging industry and commerce in general.