On May 1st 2023, United States government agencies announced the end of the requirement that international travellers (non-USA citizens/residents) show proof of COVID-19 vaccination to enter the country.
This requirement was in place for several years, prolonged every 3 months for another 3 months, until recently when it was prolonged just for one month and 1 day until May 11, 2023. Now it is official, press releases confirm as of May 12, 2023 proof of vaccination is no longer required for entry to the USA.
Read the official announcement here regarding air travel:
and here regarding land and ferry ports of entry: