Monarch butterflies migrate from Mexico to Canada and back. They do not make this migration in one year. Many of them migrate from Mexico to the California Coast where they reproduce. The next generation then migrates from California to Washington state and Colorado where they again winter over and reproduce. The final leg of the migration into Canada is made by the third generation. This process is repeated in reverse from Canada to Mexico. It is interesting to see massive numbers of butterflies all over the trees before they they fly away in mass.