Name a country with a legislative and electoral system like the US that hasn't broken down into a 2-party system. The US's system was designed specifically not to give parties power, and it broke into a 2-party system in the first month's of the first Presidential administration.

Yes - the specific parties have changed, but not since before the Civil War, because it's easier to change the existing parties than to get new ones off the ground.

Hell - the Republicans used to be the progressive party while the Democrats were the Southern slave-owning racist shitheads. Texas - the solid Republican stronghold - has only had 5 Republican governors in its history (one of which shouldn't really count since it was a Reconstruction governor), but has had 38 Democrats, and sent its first ever Republican-majority US House delegation to Congress in 2004.

It's not because Texas became super conservative. It's because the parties changed.