The only non-southern county I can find with over 50,000 votes where Wallace broke 20% is Anne Arundel (MD). Anyone know of any others?
How can you have a non-southern county in a southern state?
Obviously it depends on whether Maryland is considered a southern state, but if you consider Maryland, along with Delaware, Oklahoma, Missouri, Kentucky, West Virginia to be southern, then I can't find any large (over 50,000 votes) non-Southern county where Wallace broke 15%.
Edit: I found a few:
Butler, OH 19.2%
Wyandotte, KS 16.6%
Lake, IN 16.4%
Gloucester, NJ 15.5%
St. Clair, IL 15.1%
Genesee, MI 15.0%