A car is a must to travel throughout the counties, but avoid the Capital Beltway (I-495) during morning and afternoon rush hours. At those times the congestion is second only to that of Los Angeles.
The Capital Beltway, I–495, circles the District of Columbia through Virginia and Maryland (and enters the District very briefly, as it crosses the Wilson Bridge), providing a circular bypass for I–95 around Washington. During commute hours it becomes congested—toward Tysons Corner in the morning, and away in the evening—so if you plan to spend most of your time in downtown Washington or within the Beltway, it would be prudent to select lodging north of the I–95/I–495 interchange. Note that HOV restrictions prohibit single-person vehicles on I–66 inside the Beltway eastbound during morning rush hour and westbound during evening rush hour.
Roads that run through the region and into downtown Washington include Wisconsin, Connecticut, Georgia, New Hampshire, and Pennsylvania avenues; routes 1 and 50 (the latter turns into New York Avenue upon entering the District); Baltimore Washington Parkway; and I-295, all of which get busy 7:30-9 am and 5-6:30 pm. Giving parking tickets is one of the things capital-area jurisdictions do best, so if you park at meters, be careful and keep the meter fed. Also read parking signs carefully. There are many variations, and they are often quite confusing.
The outer loop in Maryland around the intersection with I-270 is congested in the morning rush, as is the inner loop in the evening rush. Interstate 270, which intersects with I-495 in Montgomery County, reaches destinations north of Rockville in Montgomery County. The Custis Memorial Parkway, I-66, runs east-west between Washington, D.C., and I-81 near Front Royal, which takes you south through the Shenandoah or north to West Virginia.