You may see both sumac and poison ivy along many roads, often right by the guard rails.
But the sumac you see along the highways is almost always either smooth sumac or staghorn (fuzzy) sumac, both harmless.
But the poison ivy that grows in astounding frequency along so many roads is not harmless! It can ruin your summer.
But real poison ivy is along every road, every path, every field, every vacant lot east of the Rocky Mountains, specially in the east of the US.