Here is an idea for extending Interstate 66 east through Washington. Run I-66 along VA 110 to I-395, then along the Southeast Freeway to DC 295 then to US 50. Then go along US 50 and as practical toward Dover. The only DC-area construction necessary will be a couple of ramps. The first map shows the general area.

The map below shows the route through Washington.

Existing I-66 between VA 110 and US 29 can become I-166.