If they can thrive in Canada during a free range experiment, they would most likely survive and thrive in most areas of Minnesota. International Falls is probably the exception with its impressive winter lows. We have raised Longhorns in the past and currently have 3 mother cows out of that original group. Don't become misled by the outrageous prices paid by "trophy breeders". They play their games and it has nothing to do with raising cattle.
You can raise purebred Longhorns for novelty reasons which includes personal pleasure (pasture art) or to propagate their DNA to retain genetic diversity. They serve a purpose if you can't be around to pamper your cattle. Return in a year and they will have doubled their numbers. They are a fan favorite for people looking to have the farm exemption write-off.
The purebread Longhorn will sell across the scales at about 60% compared to Angus based calves. AngusXLonghorn calves that are spotted will sell at about 70% and AngusXLonghorn calves that are solid black will sell at 80-90% as compared to Angus calves.
Pros: Cow longevity, disease resistant, almost 100% calf crop, very protective mothers, rich milkers, highly efficient
Cons: Low milkers, poor sales, very protective mothers
We use Angus/Brangus bulls since that is what we have readily available with the added benefit of the dominant polling gene. Charolais will put more pounds on and do a better job of giving a more uniform calf crop with the dilution gene. You might want to reference the other Longhorn/Charolais thread for example of their calves.
Longhorn / Brangus cross calf
Longhorn / Angus cross calves with typical line-back pattern which is a dead giveaway at the auction of their breeding (notice the pinzgauer crowd cringing)