Riding in Houston is a good way to test chains for rust. When the wind comes from the east, it brings in poisonous, corrosive chemicals from the oil and chemical operations on the eastside. When the wind blows from the south, it bring salt-laden air from the Gulf of Mexico.
ONE chain, the chain I put on my beach cruiser, has been "rustproof". It ought to be, as its advertised named is the "Rust Buster". It has a special "rust-proof" coating. My favorite chains are the Sachs-Sedis chains, but they are far from rustproof. But, the "Rust Buster" is sold only for one speed bikes.