You are not guaranteed to get a "green card" (i.e., Lawful Permanent Residence) just by marrying a U.S. citizen (a USC). In fact, if you marry for the sole reason of getting legal status, you have committed the serious crime of marriage fraud, and will be subject to deportation and a lifetime bar! Assuming the marriage was made in good faith, the answer to your question depends on several things. First, what is the immigration status of the alien spouse? If the person is here legally (a valid, non-expired Visa), the USC spouse can petition for LPR status for the alien spouse right away as an "immediate relative" of a USC. The only delay is processing time, which may be from 8-12 months. Also, if the couple have have been married less than two years, the alien spouse will be granted only "conditional residency." This means that at the end of two years, BOTH parties to the marriage must file a form and go to an interview with USCIS, to confirm that the marriage is "real" and was not a ploy to gain legal status. THEN the alien spouse gains his/her unconditional LPR. (There are a few circumstances where the alien spouse can adjust status without the USC spouse; for example, if the USC spouse was an abuser the abused alien spouse can file a waiver for the joint petition. Only a specialist can explain all these details.) If the alien spouse is out-of-status, or is undocumented, the process for gaining legal status is much more complicated -- AND MAY BE IMPOSSIBLE. SEE AN IMMIGRATION SPECIALIST for sound advice based on the facts of your particular situation.

That depends. If the Canadian citizen has a current visa, such as a K-1 visa, prior to the marriage, the adjustment of status is very quick 30-90 days usually. If, however, the spouse does not have a current visa for the US, he/she will have to begin from the beginning. This is a much longer process that involves a background check and health screening. You probably want to check into a K-3 spousal visa here: http://www.usavisanow.com/k3k4visainfo.html

If you get married, stay in the US and apply for a change of status to permanent resident, the process is approx 9months.

The processing times vary with each individual’s circumstances. Under normal circumstances, it takes around 3 to 5 months at the USCIS plus 2 to 3 months at the Consulates to process the visa.