Missouri State Missouri’s stretch of US 71 has been redesignated Interstate 49, and there’s a reason why it’s not a continuation of I-29:
The new I-49 was not called I-29 because interstate protocol requires that north-south routes increase in numerical designation from west to east.
“If it were to be named I-29, it would cross I-35 and that would be against the standard naming convention,” said Sean Matlock, transportation project manager in the Joplin office of MoDOT. “Where we are situated in Missouri, it has to be an odd number between I-35 on the west side of the state and I-55 on the east side.”
Remind me not to mention where I-40 and I-44 cross. For that matter, remind me not to mention I-99.