The Real Clear Politics final polling average showed Biden beating Trump 51.0% to 44.3%-- Biden up 6.7 points. The final polls for Reuters (by Ipsos on Nov. 1) and for the NY Times (by Siena on Oct. 30) showed Biden up, respectively by 10 and 11 points. With 99% of the vote counted, Biden did win, but just by 0.7 points-- 1,630,716 (49.5%) to 1,610,151 (48.8%), a scant 20,565 votes. In 2016 Trump managed to edge Hillary 1,405,284 (47.2%) to 1,382,536 (46.5%). Bottom line is that Trump got 204,867 fewer votes than in 2016, while Biden got 248,180 more votes than Hillary had.
Why? First of all, voters who cast their ballots for third party candidates in 2016-- 188,330 (6%)-- broke heavily for Biden this time. Geographically, Biden flipped two states counties that had gone from Obama to Trump back into the blue column: Door and Sauk. They were the only counties to flip allegiance this year. It might be worth remembering that in 2016 both Door and Sauk had been Bernie counties. The suburban counties north and west of Milwaukee-- Waukesha, Ozaukee and Washington-- while still for Trump, narrowed their margin since 2016.
More generally, Democratic performance improved in urban and suburban parts of the state, while Trump saw gains in the rural areas. One county with a significant Trump increase was Kenosha, south of Milwaukee, which went for Trump in 2016 with 47.5% but this year with 50.7%. As far as I can make out, the other big changes from 2016 to this year is that Bayfield, Menominee and LaCrosse counties became bluer, Winnebago and Calumet counties got a tad less red and Grant and Shawano counties turned more red.
The high hopes of down-ballot Democratic candidates failed against incredibly venal Republican Party gerrymandering. Democratic candidates received 46% of total votes cast in state Assembly races, but ended up with only 38 of 99 seats (winning two new districts). In state Senate races, Democratic candidates secured about 47% of total votes, but only picked up 38% of the seats on the ballot and now control only 12 of 33 seats, one less than last year. Republicans added two seats in the state Senate and came within 600 votes of securing a third district, which would have granted Republicans a veto-proof majority. Preventing that was the state Democrats' #1 priority. Democratic state Senator Patty Schachtner (SD 10) was defeated by state Rep. Rob Stafsholt while SD-30 was an open seat. Democrat Brad Pfaff beat Republican state Senator Dan Kapanke.
The two Democratic victories in the state Assembly were in the Milwaukee suburbs, where Democrats Deb Andraca (AD-23) and Sara Rodriguez (AD-13) beat, respectively, Rep. Jim Ott (R) and Rep. Rob Hutton (R).
Wisconsin Democrats didn't seriously challenge any congressional Republicans this cycle, a mistake, because without candidates firing on all cylinders, other candidates up and down the ballot suffer.