So am I to understand that major parties used to nominate their presidential candidates in early May?
Dems would have had their nom in April if it wasn’t for that fire-eater thing. Similar to how we were supposed to have it this year. Incumbent party nominates, other party nominates the following month. (July and Aug was the original plan for 2020.) The longer campaign season in 1860 may be due to our primary season, not a thing in 1860.