From: utzoo!decvax!harpo!ser Newsgroups: net.general Title: Re: Interstate Highway numbering - (nf) Article-I.D.: harpo.1066 Posted: Thu Sep 23 09:01:25 1982 Received: Mon Sep 27 19:58:51 1982 #R:ihuxu:-11000:harpo:800017:000:236 harpo!ser Sep 23 08:53:00 1982 If I remember correctly, odd prefixes on three digit interstates indicate "spurs", i.e., routes into or out of major cities, while even prefixes indicate "circuits", i.e., routes around major cities. Steve Riegel harpo!ser