Exit polling indicates that Barack Obama has won the Democratic primary in Virginia, his sixth straight victory over Hillary Clinton.

UPDATE (7:36 p.m.): GOP race in Virginia is too close to call.

UPDATE (7:42 p.m.): Maryland polls to remain open until 9:30 p.m. because of weather and traffic problems.

UPDATE (8:30 p.m.): John McCain has been projected the winner of the Republican primary in Virginia. Does this finish off Mike Huckabee?

UPDATE (9:30 p.m.): Maryland goes to Obama and McCain.

UPDATE (9:41 p.m.): Put D.C. in the Obama win column.

UPDATE (9:45 p.m.): McCain joins Obama in a sweep of the Potomac primary.

For up-to-date results and delegate counts, click here for an interactive map courtesy of the Associated Press.