You'd probably know more on this than I do, Medina, but I would guess that the Midwest in general has gotten less blue as the strength and numbers of big labor have declined.
Ohio has but only slightly until 2016 and you have to go back almost 50 years to find a Presidential election in which Ohio voted more Democratic than the nation as a whole. As noted above, Ohio has voted for the winner in 15 straight Presidential elections (starting with 1964) so the Buckeye State has, for the last ~60 years, been pretty much even with the nation as a whole. I believe that Ohio's 52 year streak of voting for the winning Presidential candidate is the longest such streak in the nation. Lately, however, Ohio has typically been slightly to the right of the national vote so it is basically just a matter of time until Ohio votes for an unsuccessful Republican candidate:
- In 2016 the national popular vote was 48/46 D while Ohio was 52/43 R so Ohio was ~3-4 points to the right.
- In 2012 the national popular vote was 51/47 D while Ohio was 51/48 D so Ohio was slightly to the right.
- In 2008 the national popular vote was 53/46 D while Ohio was 51/47 D so Ohio was ~1-2 points to the right.
- In 2004 the national popular vote was 51/48 R while Ohio was 51/48 R so Ohio was close to dead on.
- In 2000 the national popular vote was almost exactly even while Ohio was 50/47 R so Ohio Was slightly to the right.
- In 1996 the national popular vote was 49/41 D while Ohio was 47/41 D so Ohio was slightly to the right.
- In 1992 the national popular vote was 43/37 D while Ohio was 40/38 D so Ohio was slightly to the right.
- In 1988 the national popular vote was 53/46 R while Ohio was 55/44 R so Ohio was slightly to the right.
- In 1984 the national popular vote was 59/41 R while Ohio was 59/40 R so Ohio was close to dead on.
- In 1980 the national popular vote was 51/41 R while Ohio was 52/41 R so Ohio was slightly to the right.
- In 1976 the national popular vote was 50/48 R while Ohio was almost exactly even so Ohio was slightly to the right.
- In 1972 the national popular vote was 61/38 R while Ohio was 60/38 D so Ohio was slightly to the left.
- In 1968 the national popular vote was almost exactly even while Ohio was slightly to the right of that.
- In 1964 the national popular vote was 61/39 D while Ohio was 63/37 D so Ohio was slightly to the left.
- In 1960 the national popular vote was almost exactly even while Ohio was 53/47 R so Ohio was slightly to the right.
Note that Ohio was more Democratic than the nation as a whole in 1964 and 1972. Ohio was only slightly to the right in all of the other elections since 1960 until 2016 when Ohio was substantially more Republican than the nation as a whole.
There is a trend but it is pretty minor. From ~1960-1972 Ohio was slightly more Republican than the country twice and slightly more Democratic twice. After that Ohio became consistently more Republican but only by a VERY thin margin so that isn't much change.
If you graphed this all out for the Great Lakes States I think you'd see roughly the same thing in MN, WI, MI, and PA. They have all probably drifted slightly to the right and then moved sharply right in 2016. The interesting thing to see, going forward, will be if that right turn in 2016 is a trend that future Republican candidates can maintain or even grow (possibly taking Minnesota where Trump lost by about 1.5%) or if it is a one-time phenomena that future Democratic candidates can reverse.
Close states in 2016:
States that Tump won by <8%:
- 16 EV's, Michigan, Trump won by 0.23%
- 20 EV's, Pennsylvania, Trump won by 0.72%
- 10 EV's, Wisconsin, Trump won by 0.77%
- 29 EV's, Florida, Trump won by 1.20%
- 1 EV, Nebraska 2nd District, Trump won by 2.24%
- 11 EV's, Arizona, Trump won by 3.55%
- 15 EV's, North Carolina, Trump won by 3.66%
- 16 EV's, Georgia, Trump won by 5.13%
Note that Ohio is conspicuously absent from this list. For decades Ohio has been a swing state if not THE Swing State but in 2016 Trump won Ohio by a comfortable 8.13% margin (slightly to the right of Georgia and just left of Texas).
States that Clinton won by <8%:
- 4 EV's, New Hampshire, Clinton won by 0.37%
- 10 EV's, Minnesota, Clinton won by 1.52%
- 6 EV's, Nevada, Clinton won by 2.42%
- 2 EV's, Maine at-large, Clinton won by 2.96%
- 9 EV's, Colorado, Clinton won by 4.91%
- 13 EV's, Virginia, Clinton won by 5.32%
This really demonstrates how precarious Trump's 2016 win was. He won 102 EV's by <5% and 115 by less than 6%. Even a leftward shift of just 1% would flip the election. Meanwhile, Clinton only won 31 EV's by <5% meaning that a rightward shift wouldn't change much because there aren't many competitive states that Clinton actually won.
Assuming that the seven "faithless electors" would have voted for the candidate that won their state if it mattered:
- Clinton won 232 EV's.
- Trump won 306 EV's.
Won by at least 1%:
- Clinton won 228 EV's by at least 1% (subtract 4 NH)
- Trump won 260 EV's by at least 1% (subtract 16 MI, 20 PA, 10 WI)
Won by at least 2%:
- Clinton won 218 EV's by at least 2% (subtract 10 MN)
- Trump won 231 EV's by at least 2% (subtract 29 FL)
Won by at least 3%:
- Clinton won 212 EV's by at least 3% (subtract 6 NV)
- Trump won 230 EV's by at least 3% (subtract 1 NE 2nd)
Won by at least 4%:
- Clinton won 212 EV's by at least 4% (none 3-4%)
- Trump won 204 EV's by at least 4% (subtract 11 AZ, 15 NC)
Won by at least 5%:
- Clinton won 203 EV's by at least 5% (subtract 9 CO)
- Trump won 204 EV's by at least 5% (none 4-5%)
Won by at least 6%:
- Clinton won 190 EV's by at least 6% (subtract 13 VA)
- Trump won 188 EV's by at least 6% (subtract 16 GA)
The next closest states after that are Ohio (18 EV's Trump won by 8.13%) and New Mexico (5 EV's Clinton won by 8.21%).