Identifying Ailanthus (Tree of Heaven)

The Ailanthus is an invasive species of tree in Ohio.  It is common in this area, and is spreading rapidly.  It is often mistaken for Black Walnut and allowed to grow, producing massive amounts of seed and reproducing.
It forms thickets, crowding out more desireable species of trees.  It is a fast growing, short lived tree, and the wood is not useful for timber or for firewood.  Once established, it becomes difficult and costly to eradicate, so keeping an eye out for young trees and removing them immediately is prefered. 

Here is an easy way to discern between the compound leaves of young Ailanthus vs Black Walnuts. 
Ailanthus has less than ten pairs of veins in each leaflet, and has a notch at the base of each leaflet.
Black Walnut has more than 10 pairs of veins in each leaflet, and does not have a notch.