The size is estimated. It might be 7mm, but not much bigger.

This is Lasiopogon currani, a small asilid that ranges from Ontario south to Georgia in, and east of, the Appalachian Mountains. It's a small species in a genus of small robber flies; Tom is right, it ranges in length from about 6 to 8 mm. This is a dark specimen; many have reddish tarsi, tibiae and genitalia and the third antennal segment is often reddish, too. The giveaway here (if you can see it) is that the top surface of the halter is completely black. This is the only Lasiopogon in the region that has this character.