Part of
milkweed butterfly genus Danaus
in
four-footed butterfly family Nymphalidae
in
butterfly/moth order Lepidoptera
in
🐞︎🐛︎🐜︎🐝︎ insect class Insecta.
Native to much of North America, plus Central America and northern South America, extending to islands across the Atlantic and Pacific Oceans.
The butterfly is famous for its migration from their wintering grounds in central 🇲🇽 Mexico, following the spring flowers of
milkweed genus Asclepias and related genera
(the only host plant on which monarch's eggs and larvae will grow and survive!) north through the 🇺🇸 USA and 🇨🇦 Canada, summering in a surprising large area, before following the late-season flowers back to their wintering grounds. Learn more about this amazing story!
(Of course, other population have different migration patterns, and some populations have no need to migrate at all!)
Poster of monarch butterfly Danaus plexippus lifecycle, larval host plants, adult nectar plants, and growing info for these plants. 
Mowing and Management: Best Practices for Monarchs.
For agricultural producers and land managers (USDA)
Xerces Society