An unlucky number, Route 13 was never assigned, for the safety of Connecticut drivers. Believing in lucky and unlucky numbers is considered silly but still widely practiced. Route numbers such as 4, 7, 8, 13, 17, 23, 69, 420, and 666 may carry extra significance among drivers and residents.

In the past, some route numbers have had to be changed:

• In the 1930s, California state route 17 was originally called CA 13, but was changed because of objections to the number. (Another CA 13 was constructed nearby in Oakland.)
• In 1967, the New Jersey DOT, in response to sign theft, renumbered Route 69 to Route 31.
• In July 2003, US 666 in the Southwest was renumbered to US 491.

There was never a Route 13. But was there?

However: in 1934, the biennial report to the highway commissioner mentions design work on "Route 13" in New Britain. Possibly the writer meant pre-1932 route 113 (now Route 175); but the one-line mention doesn't provide enough information.