IT is an irony worth noting: Virginia, whose delegation across the Potomac is perennially the most conservative in Congress, and whose capital, Richmond, was the seat of the Confederacy, has become the leading benefactor of the federal budget.
On a per-person basis, Virginians received $4,503 in federal outlays in fiscal 1983, some $25 billion in all, in grants to state and local government, salaries, procurement contracts, and so forth.
Virginians might have lost to the Union forces, but they do have the Pentagon on their side of the Potomac: More than half of Virginia's federal take, $14 billion, was for defense contracts.
More liberal Maryland, Virginia's rival today for the residences of congressmen as well as federal jobs and grants, did almost as well, ranking third in federal spending with $4,211 per person, behind second-place Alaska.
Evidently, while congressmen like to boast that their first interest is their district back home - where they sometimes rent apartments or check into hotels - they appear to have looked after their ''adoptive'' Washington neighborhoods rather more than they like to say.