Considering using E-Verify?
E-Verify was originally voluntary, but many states now require its use for certain employers.
Requirements vary—some states mandate it for all businesses, while others apply it only to public employers or contractors.
A few states limit its use, while many have no requirement.
Check out this link from Equifax (there is a clickable map) for details on E-Verify mandates, penalties, and applicable laws.
https://workforce.equifax.com/e-verify-state-requirements
PS: I suspect (but may be wrong) that E-verify will be required for everyone soon.