This large insect was sitting near the top of a picnic table umbrella at my uncle's house. It sat without budging for a long time allowing many pictures, which was good because it was perched well above my head. This is one of the largest insects I have seen in the area, measuring a little over two inches long if you include the legs. It is also very pretty, with an intricate pattern on its wings and an interesting black and gray coloration of its thorax.
It looks a bit like a water strider or giant mosquito, or even a harvestman (a.k.a. daddy-long-legs), but it is not any of those. Instead it is crane fly, a member of the family Tipulidae. There are so many genera and species in this family that it is difficult an individual beyond the family level. Based on the Kaufman guide, I think this insect belongs to the genus Tipula, which itself has about 480 species. BugGuide.net shows a very similar-looking species called the Giant Crane Fly (Tipula abdominalis). This species is found in eastern North America and usually has an early season brood (May/June) and a late season brood (September/October), which makes it a good candidate for the season and range.
If you look closely at its head, you can see the long mouthparts and short antennae typical of flies generally and crane flies specifically. The tapered abdomen (visible in the first photo) suggests that this is a female.
Crane fly larvae are aquatic and feed on decomposing vegetation. Since larvae are sensitive to pollution, the EPA uses their presence as one of the indicators of a clean waterway. Adults are slow fliers and tend to be more active at dawn and dusk. Since their adult life span is very short, mating and egg-laying are the main priorities. Crane flies are harmless to humans.
For more information on crane flies in eastern North America, see The Crane Flies of Pennsylvania.