Nice to have you with us. What Thamnophis species are you thinking about getting. Looks like you've got a couple species in your state.
Thamnophis sirtalis sirtalis - Eastern garter snake and Thamnophis sauritus sauritus (Eastern ribbon snake). The eastern garter would be the easier to keep. We might have some members close to you who can supply you with a captive bred snake. Here's a link to the forum care sheet. Be sure to ask all the question you might have. We are here to help.
Garter Snake Forum - Garter Caresheet