How long can a Canadian citizen married to a US Citizen stay in the US?

I married a Mexican citizen in Mexico and I am a US citizen, and we currently live in Mexico. You can only live in Mexico for the time they alloted on your white paper when you entered the country, usually it is 90-180 days. During that time you should apply for a FM2 at the Immigration office. An FM2 is a visa that allows you to live in Mexico. You would qualify for it because you are married to a Mexican citizen. An FM2 is good for as long as you want provided you renew it every year and you can become a citizen after having it for 2 years. FM2 allows you do live and participate as a Mexican citizen would. I currenlty have an FM3, which is a working visa. I got it through my employer. If you want to work in Mexico you could get an FM3 and that would also allow you to stay in Mexico, but it needs to be renewed every year. Good luck and I hope that this helps a little.