Polymarket has been live in the US since the beginning of the year. There is a queue but it’s absolutely live. And before that you could still use it so long as you did not use a VPN.
> Restricted Jurisdictions. You acknowledge and agree that you are not permitted to access, use or trade with the Contracts on the Platform if you are residing in, a citizen of, organized in or located in the following jurisdictions (collectively, the “Restricted Jurisdictions”): Australia, Belgium, France, Germany, Italy, the Netherlands, Ontario, Poland, Quebec, Russia, Singapore, Taiwan, Thailand, the United Kingdom, the United States; or a jurisdiction or territory that is the subject of comprehensive country-wide, territory-wide, or regional economic sanctions by the United States, including but not limited to Iran, Syria, Cuba, North Korea, and the Crimea, Dontesk and Luhansk regions of Ukraine.