My shortest logged segment in Travel Mapping is easily the 0.02 miles of MN 292 between its western junction with US 61/63 and E 7th St. I used that tiny segment essentially to turn around/backtrack on E 7th St due to missing an earlier turn.
Of course, MN 292 is only 0.48 miles in total, which leads to the very odd situation of my having been on less than 5% of a route less than a mile long.
This means the route shows up as red under "routes closest to clinched". I've wondered if I'm the only one to have a red route in that category (most are obviously blue/green due to being close to clinched, but in this case, 0.46 miles is not close to being clinched in percentage terms!)