This chart (or should we say charts) from the Inrix Scorecard shows the diurnal, weekly, monthly, and trend levels from INRIX. There is more congestion in the morning and especially the evening. Thursday evening gets more traffic than any other day, though Friday afternoon is higher, and Tuesday wins the morning. It’s all very proprietary, but traffic congestion overall seems to be hovering pretty constant between 2010 and 2013.
At any rate, Minneapolis comes in at 16th (Yay, we have traffic, we are not dying [like some other Midwestern cities we could name]) (Boo, we have traffic), which is not surprising given it is arguably the 13th largest metro area in the US (it all depends on definitions).
How many years has INRIX gathered this data? It would be interesting to make more year over year comparisons going back the past two decades or more.
INRIX is reporting what they have, this is all GPS-based data, so sample sizes get very small a few years ago. TTI (using loop detectors) goes back to the 1980s, but I think that data is suspect since again sample sizes were relatively small.