Each fall, millions of monarch butterflies leave their summer breeding grounds in the northeastern U.S. and Canada and travel upwards of 3,000 miles to reach overwintering grounds in southwestern Mexico.

Link: https://news.nationalgeographic.com/2017/10/monarch-butterfly-migration/?utm_source=Twitter&utm_medium=Social&utm_content=link_tw20171018news-monarchbutterflies&utm_campaign=Content&sf122929412=1