Hard to say about 2020, but here's the result if Trump were teleported backwards to 1856 (...or if you just compare statewide percentages between Trump and Buchanan). Trump ran about a percentage point ahead of Buchanan nationally, 46%-45%, and wins the Electoral College 169-127. Alabama was interestingly an exact tie -- Trump and Buchanan both received 62.08% -- but I awarded the state to Trump as he had the larger margin against his main opponent. I gave South Carolina to Buchanan partially to cancel this out and partially because the 1850s Democratic legislature would've been unlikely to grant the state's votes to Trump.
Trump would carry his home state against Buchanan!
