"It can be a ground cover, or shrubby, or a woody vine (called a liana), achieving nearly treelike proportions. Its leaves can be shiny or matte (even in the same population), in various shades of green (or red-bronze, upon emergence), and they vary in size and shape, with margins from smooth to toothed or deeply lobed."
“In one area in Quebec,” Ms. Pell said, “it has straplike leaflets and looks like a fern. In the Southeast, I have seen leaflets as long and wide as my head, and elsewhere, often very close by, leaflets shorter than my thumb.”
"Remember that any tools you use and garments you wear will be tainted with urushiol, and unless they’re thoroughly cleaned they can transfer it to your skin. Carefully bag any debris for the trash, but don’t add it to a burn pile: Urushiol can be released in smoke and will damage lungs.And don’t make the mistake of thinking that it will wear off over time.“I have heard of rashes caused by contact with tools that hadn’t been used in two years, but still had resin on them,” Ms. Pell said. Researchers referring to old herbarium specimens in scientific collections have likewise had reactions to the dried, pressed plants."
More information re identification and management of poison ivy at the New York Times.
I know of one huge patch of poison ivy on a golf course in northern Minnesota. Since I'm not sensitive to the oil, I have on occasion waded in to retrieve errant drives, once emerging with my ball and twelve others.