This is a population distribution map for the known range of the Tegenaria agrestis (Hobo Spider). The red "dots" are isolated populations, and are from "hitchhiking" on vehicles, interstate commerce, etc. (Red dots: 2 in Montana, 3 in Wyoming, and 2 in Colorado)
Adapted from
http://www.washington.edu/burkemuseum/spidermyth/images/hobomap.gif