For tourist visits to Canada of less than 180 days, U.S. citizens do not need visas. Other types of travel (e.g., to work, study, or immigrate) generally requires visas.
Anyone with a criminal record (including misdemeanors or alcohol-related driving offenses) may not be able to enter Canada without first obtaining an approval for rehabilitation well in advance of any planned travel. To determine whether you may be inadmissible and how to overcome this finding, please refer to the website link below.
Entry into Canada: Entry into Canada is solely determined by Canada Border Services Agency (CBSA) officials in accordance with Canadian law. Canadian law requires that all persons entering Canada carry both proof of citizenship and proof of identity. A valid U.S. passport, passport card, or NEXUS card satisfies these requirements for U.S. citizens.
Please refer to the CIC website for all travel information.