In Indiana...
Indiana lets school districts decide. The district I went to (and sub for the most) requires 15 college credits, another requires a clean drug test and 30 credits, two require 30 credits or a sub certificate from another district, one requires 60 credits, and another requires 60 credits or a sub certificate from another district. All require a clean background check.
The urban district near me requires a bachelor's degree. They pay a lot more, but I had to do methods and field experience in several of the schools and there's only a few I would CONSIDER subbing for. Let's just say kids are allowed to cuss, and the school is lax when it comes to discipline.