Today, October 17, 2018, Canada announces the national legalization of marijuana. But what does this mean for travelers? Marijuana use can still be regulated by cities. For example, the city of Calgary in the province of Alberta has banned the use of recreational marijuana in public and can be forbidden in housing agreements between landlords and tenants. Additionally, although recreational marijuana use is legalized in Canada, it is illegal to bring marijuana purchased in Canada across the border into the United States – even if flying into a state where marijuana is legal. When traveling to the country, beware of the age limit (nationally 18 years of age, but some provinces have set the age limit to 19), beware of the city rules and regulations of marijuana, and remember it is illegal to transport marijuana from Canada into the United States.
https://www.cnn.com/travel/article/traveling-with-marijuana-in-canada/index.html