Is P2P legal in the US?

Could you please clarify for me if Peer-to-Peer (P2P) transactions involving cryptocurrency are considered legal within the United States? I'm interested in understanding the regulatory framework surrounding such activities, particularly with regards to taxation, anti-money laundering measures, and consumer protection. Additionally, are there any specific states or regions within the US that have enacted stricter or more lenient laws pertaining to P2P cryptocurrency transactions? Your insights would be greatly appreciated.