Separate ideology (or whatever happens to be the object of bias) from identity, and you're halfway there. People are much more amenable to changing their minds if their identities aren't at stake. For example, most people can discuss the pros and cons of F-150s and Silverados fairly rationally; those with the Calvin pissing logos, not so much.
On a societal level, your guess is good as mine. Perhaps increased infrastructure spending so that high-skill, high-pay jobs are more evenly spread out and ideological segregation is reduced?
On an individual level, being active in (non-political) hobbies and volunteer groups can help, especially ones that attract both people from the cities and the countryside.
Who am I stereotyping? People with "Calvin pissing on Ford/Chevy/Ram logo" stickers? The vast majority of truck drivers don't really care about brand--they just want the most appropriate truck for their situation.
