I-194  Michigan (link)

3.38 miles [1]; from I-94 north to Michigan Avenue in Battle Creek. Locals call this highway the Penetrator [4], which thankfully has not been used for the name of a breakfast cereal. Interstate 194 dates back to about 1963.

At an indeterminate time in the past, back when the freeway was called MI 78, there were plans to build the freeway south of I-94 as well, in the path of current MI 66, ending a mile or so north of Joppa. There would be interchanges at Beckley Rd and at Graham Lake. [3] There's no evidence yet that this would have been called I-194 as well. See also:

• I-194 (Michigan Highways, Chris Bessert)
• Interstate Guide: I-194 (AARoads)

I-194 (not signed as interstate)  North Dakota (link)

1.20 miles [1]; from I-94 in Mandan to US 10 in Bismarck. The route is not signed as I-194. [2]

See also:

• I-194, Bismarck-Mandan, Highway Feature of the Week (Michael G. Koerner)
• Interstate Guide: I-194 (AARoads)

Sources

1. Route Log and Finder List - Interstate Highways, FHWA, Oct. 31, 2002.
2. "FMaier3." "I-194." Personal email, Aug. 31, 2000.
3. Peacock, Bobby. "Michigan I-194." Personal email, July 8, 2001.
4. "Penetrator to get $1.6M face-lift." The Enquirer (Battle Creek, Mich.), March 18, 2002. (Thanks to William F. Yurasko)