Marysville has one auto plant that builds mainly Accords and perhaps some (?) Civics while another plant is in nearby East Liberty is building CRVs. Russell's Point, OH has a transmission factory and the engine factory is in Anna, OH about 45-min north of me on the western end of the state. I'm fairly certain that OH offers tax advantages for plants in different counties which is only fair. The problem with putting everyone in/near one town, such as Marysville, is the limited number of suitable workers available for expansion. As it is, Honda is the largest private employer in Central OH.
The factory in Greensburg, IN builds Civics and the plant in Lincoln, AL east of Birmingham, produces the large platform vehicles - Odyssey, Passport and Ridgeline - so it may be last in line for electric conversion? I'm not sure what they're building there now but there is a Honda plant in Alliston, Ontario, just across the river from Detroit and for a long time they built Civics for the US and Accords for Canada.