US travel to Canada is moderated by the border officials of CBSA.

US Travel to Canada Requirements
The requirements to travel to Canada from the USA will depend on citizenship and VISA status. If you are a US citizen travelling to Canada, you shouldn’t have to worry about Visa requirements. However, there are restrictions that apply.
US Travel to Canada Restrictions
Travelling to Canada from the US is moderated by law regarding criminal records. Individuals who have a history of criminality will be stopped or denied entry to Canada depending on their charges. If you have a criminal record and wish to enter Canada, you may require a waiver.