New Jersey Gov. Phil Murphy signed into law a measure requiring that residents carry health insurance or pay a penalty.
The legislation comes in response to congressional Republicans' repeal of the mandate contained in the Affordable Care Act in last year's tax bill.
The law's sponsors say the requirement keeps health insurance markets afloat. Roughly 800,000 have insurance through the law and the expansion of Medicaid.
Residents face a penalty of 2.5% of income or $695 per taxpayer, whichever is greater. A family's maximum penalty is $2,085.
Murphy, a Democrat, signed the law Wednesday after promising to push back against GOP attempts to weaken or repeal former President Barack Obama's landmark legislation.
A handful of other states were considering similar measures. Massachusetts already has a mandate in place.