Originally Posted by downtube42

The shortest time was 7 days 15 hours in 2014 (Christoper Strasser), the longest time prior to this year was 10 days 16 hours in 1983 (Lon Haldeman).
Distance has ranged from 2901 to 3170 miles.
Average speeds have ranged from 12.3 (Haldeman) to 16.4 (Strasser).

In 2021, duration was 11 days 3 hours, about 9 hours more than Haldeman.
Distance in 2021 was about the midpoint at 3037 miles.
Average speed in 2021 was 11.8, about 0.5 mph slower than Haldeman.

It is accurate to say the average speed in 2021 was the lowest in the history of the event.

Weather is obviously a huge factor, and we don't have data that can measure the impact of weather year over year.