Do legal requirements differ from state to state?
Yes and no. The federal Electronic Signatures in Global and National Commerce law and the state Uniform Electronic Transactions Acts (UETA) are similar in substance, and together enable the use of electronic signatures in commerce throughout the US. That said, there may be additional regulations, or compliance requirements, that apply to certain processes (like truth-in-lending disclosures, or protecting the privacy of medical records). But these requirements exist for paper processes as much as for electronic ones.