How interstate numbers get assigned? by Bob D?

Question

How and why did I-95 get its designation?

Answer 1

Highway Numbering System
In 1925, the American Association of State Highway and Transportation Officials set the guidelines for numbering interstates and U.S. highways. Some of these guidelines are:

Interstate north-south routes have odd numbers, with numbers increasing from west to east.
Interstate east-west routes have even numbers, with numbers increasing from south to north.
Interstate highway routes have one- or two- digit numbers.
North-south interstates ending with a 5 and east-west interstates ending with a 0 are typically major cross-country routes.
A three-digit interstate always ends with the two-digit number of the main interstate it loops off from, except I-238.
Three-digit road numbers beginning with an even number are either beltways that go around a city or freeways that go through a city.
Three-digit road numbers beginning with an odd number branch off the main interstate.
U.S. highway north-south routes have odd numbers, with numbers increasing from east to west.
U.S. highway east-west routes have even numbers, with numbers increasing from north to south.
U.S. highway east-west routes ending in 0 tend to be cross-country routes.
Three-digit U.S. routes contain the two digits of their parents routes, but there is not an odd and even number system.
See also: American Association of State Highway and Transportation Officials website: http://www.transportation.org/

Source: Summarized from an article in Via, March/April 2000. p.13.

Answer 2

http://msxml.excite.com/info.xcite/search/web/interstate%2Bhighway%2Bnumbers