MILKWEED BY STATE and COUNTY
The Biota of North America Program has a webpage of images showing the distribution of each milkweed species by state and county.
MILKWEED SPECIES GROWING GUIDES
Monarch Watch then provides a comprehensive list of growing characteristics and conditions of each milkweed species.
WHERE TO GET MILKWEED
Here's a state by state list of milkweed plant and seed sources. Try to find milkweed local to you, as it will be more adapted to your specific local climate conditions.
OTHER PLANTS THAT ATTRACT INSECTS
Pollinator Partnership has native nectar plant guides to help insects such as butterflies. Just enter your zip code and learn what plants work in your area and how to care for them. Also check out the Xerces Society clickable map that has tons of pollinator and ecosystem info.