Options for equalizing temperature between the basement and the rest of the house in summer?

I live in a pretty old house in the midwest, built 1929, bought in '21, single-story, ~1300ish sqft, and with a large, spacious basement. Every time summer comes around I've had issues with the basement getting MUCH colder than the rest of the house (like >10 degrees F difference), presumably due to poorly-insulated floors and...