Poison Ivy Geography:

Poison Ivy is found everywhere east of the Rocky Mountains. It has also been reported in some northwestern states like Washington and Oregon. It is rarely found above 4,000 feed elevation.

It is very hardy and adaptable, and can grow in areas with as little as 8 to 10 inches of annual rainfall. Poison ivy seems to grow best in moist, slightly shady areas, but can also thrive in open areas with adequate moisture.