I want to be able to send an address anywhere in the USA and get back flood risk data.
FEMA houses flood plain maps. If you give them an address, you just get a map, and you have to look at it to find the location's flood risk by hand.
You can do slightly better with inputting a single address on FloodSmart.gov, but the result is a page that does not render with the address in the link.
FEMA has some APIs, but I an having a hard time seeing one related to flood.