So I divided the state population into quarters and then counted up all the votes from the 92 counties with the counties ranked from most votes to least votes. Each quarter has exactly 25% of the vote +/- 1. The "line counties" I divided equitably into each quarter to get the 25% division. So for example, the 3rd-largest county in number of votes in 2020, Hamilton, took the 1st quarter above 25%. So to get everything to equate, 76.2% of the Hamilton county vote counted into the 1st quarter and 23.8% into the 2nd quarter.
Here's elections I've done so far. My goal is to do the presidential, governor, and Senate elections going back to 2000 (thank you to the asshole Wikipedia editor for 2016 on back that combined the Libertarian and write-in vote into "Other" and made by job harder).
2020 President
1st Tier: Marion, Lake, plus 76% of Hamilton
2nd Tier: 24% of Hamilton, Allen, St. Joseph, Hendricks, Porter, Johnson, Vanderburgh, Elkhart, and 32% of Tippecanoe
3rd Tier: 68% of Tippecanoe, Monroe, Clark, Madison, LaPorte, Delaware, Vigo, Hancock, Floyd, Howard, Boone, Bartholomew, Morgan, Kosciusko, Warrick, Wayne, Grant, Dearborn, and 56% of Dubois
4th Tier: 44% of Dubois plus all remaining counties
Tier 1: Biden +136,592 (Biden 58.1%, Trump 40.1%, Jorgensen 1.8%, Other 0.1%)
Tier 2: Trump +96,333 (Trump 55.3%, Biden 42.6%, Jorgensen 2.0%, Other 0.1%)
Tier 3: Trump +156,518 (Trump 59.3%, Biden 38.6%, Jorgensen 2.1%, Other 0.1%)
Tier 4: Trump +371,100 (Trump 73.5%, Biden 24.6%, Jorgensen 1.9%, Other 0.0%)
2020 Governor
Tier 1: Myers +23,761 (Myers 47.7%, Holcomb 44.6%, Rainwater 7.7%)
Tier 2: Holcomb +189,320 (Holcomb 57.7%, Myers 32.7%, Rainwater 9.6%)
Tier 3: Holcomb +216,206 (Holcomb 58.4%, Myers 29.8%, Rainwater 11.8%)
Tier 4: Holcomb +356,841 (Holcomb 65.3%, Myers 18.1%, Rainwater 16.6%)
2016 President
Tier 1 line is 77% of Hamilton, Tier 2 line is 52% of Tippecanoe, Tier 3 line is 87% of Henry
Tier 1: Clinton +100,579 (Clinton 54.2%, Trump 39.6%, Johnson 4.8%, Other 1.4%)
Tier 2: Trump +129,121 (Trump 56.1%, Clinton 37.3%, Johnson 5.0%, Other 1.7%)
Tier 3: Trump +168,334 (Trump 59.0%, Clinton 34.6%, Johnson 5.1%, Other 1.3%)
Tier 4: Trump +327,284 (Trump 71.0%, Clinton 23.6%, Johnson 4.6%, Other 0.9%)
2012 President
Tier 1 line is 65% of Allen, Tier 2 line is 32% of Monroe, Tier 3 line is 79% of Henry
Tier 1: Obama +126,397 (Obama 58.7%, Romney 39.5%, Johnson 1.5%, Other 0.2%)
Tier 2: Romney +116,462 (Romney 57.9%, Obama 40.2%, Johnson 1.7%, Other 0.3%)
Tier 3: Romney +90,642 (Romney 55.7%, Obama 41.9%, Johnson 2.2%, Other 0.2%)
Tier 4: Romney +186,949 (Romney 63.0%, Obama 34.6%, Johnson 2.3%, Other 0.1%)
I'm definitely going to do Obama 2008 and Joe Donnelly 2012.