Not Ailanthus altissima (Simaroubaceae) - bark shown is plated and furrowed.
Not Sambucus canadensis, which is an oppositely arranged compound leaved species. This plant is alternately arranged.
I agree with another round of information, including collection of a branch in order to get some closeup images of stem, leaf, and buds. Also pics of the entire tree in its situation, and maybe closer shots of its main trunk.
I'm leaning toward some kind of nut tree, though there are plants like Toona sinensis (Meliaceae) that favor this look. These images are from a series of fine old specimens growing in Durand Eastman Park, Rochester NY (circa 2008).
Black Walnut Juglans nigra for me - the bark is too rough and fissured for Ailanthus, OK for Black Walnut; also the leaves don't have the basal lobules that Ailanthus usually shows. Not sure I can exclude Toona sinensis as a possibility though (ages since I've seen that!).
Here are some more images of Toona sinensis from the Rochester trees.
I can't see the bark clearly enough on the images RosinaBloom has provided thus far to say. Chinese Toon has plating and exfoliating bark, and I find that quite different from Black Walnut - which is usually ridged and furrowed.
Here are some additional images for Toona sinensis.
First image is an old tree at Monticello - Thomas Jefferson's estate in Virginia outside Charlottesville.
Two through four are an old tree at the Swannanoa estate (built by James Dooley in the 1920s), near the Blue Ridge Parkway where it intersects with I-64 in western Virginia. Many old conifers on that property, too.
Fifth image are open seed capsules from Toona sinensis - I am fascinated by their resemblance to flowers opening.
lol. RosinaBloom pointed out the upward growth/leaves which are more downward in Ailanthus. The venation looks right, colour, etc. I'm convinced it is Toona. A trunk photo would help solve this one. Thanks VV.