From: utzoo!decvax!cca!ima!johnl Newsgroups: net.followup Title: Re: Interstate Highway numbering Article-I.D.: ima.220 Posted: Sat Sep 18 14:10:34 1982 Received: Wed Sep 22 08:13:50 1982 References: ihuxu.110 Interstate routes are numbered fairly rationally. East-west main routes get even numbers less than 100 and north-south routes get odd numbers less than 100. Numbers generally increase from southwest to northeast so in San Diego there are routes 5 and 8, and here in Boston we have 90, 93, and 95. Main long-distance routes get numbers that end in 0 and 5, so that 95 runs from Maine to Florida but 89 only goes from Concord NH to Montreal. For the three digit numbers, the first digit is even if it's a bypass that comes back to the main highway and is odd if it's a spur. The last two digits are the main route that it connects to. For example, 495 is a loop around Boston that connects to 95 at both ends, but 195 is a spur from Providence out toward Cape Cod. Anomalies occur, particularly in dense areas like New York, so don't write back to me with counterexamples; these are general rules. But basically, who cares? John Levine, decvax!cca!ima!johnl, harpo!esquire!ima!johnl (uucp) Levine@YALE (Arpa), 617-491-5450 (desperation)