Interurban is generally used to describe transportation. As a noun (as in "In those days you could take the interurban from Seattle to Tacoma"), interurban has meant a fairly heavy but fast electric train, something between an urban trolley and a full-fledged long-distance train, that offers more frequent service than an ordinary railway. Interurban transit today may include bus, ferry, and limousine—and, in a few lucky areas, a regional railway. With oil supplies dwindling, there's hope that interurban railways will be coming back into wider use.