Minneapolis average annual snowfall is 54" so I'm not sure where this 9" greater then Chicago is coming from, unless we are talking about median.
Here is annual snowfall over the past 10 seasons. Yes we've had some big time clunkers but the retention is a much greater here then in the Chicagoland area. Also worth noting Minneapolis averages about 8" less of liquid equivalent precipitation so our climate is drier by comparison.
2019-2020
51.5
2018-2019
77.1
2017-2018
78.3
2016-2017
32.0
2015-2016
36.7
2014-2015
32.4
2013-2014
69.8
2012-2013
67.7
2011-2012
22.3
2010-2011
86.6
AVERAGE NUMBER OF DAYS
* WITH SNOW "ON GROUND"
* ---------------
* DAYS INCHES
* 100 ... 1
* 79 ... 3
* 54 ... 6
* 34 ... 9
* 24 ... 12