US/Interstate Highway Trivia

Subject: Highway Numbering System NVC

There's a good reason there's no
U.S. Highway 1 in California
(but there is a U.S. 101):

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.

And while on the subject:

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.