Pam Fessler (back on the beat!) at NPR:

ince 1995, federal law has required states to offer people a chance to register to vote when they visit a local motor vehicle office.
But it turns out that Pennsylvania, like some other states, was asking that question of everyone who applied for a driver’s license or state ID card — even those showing green cards or other documents identifying them as noncitizens.
That is often confusing for immigrants who come in to get a driver’s license or ID, which noncitizens are eligible to do.
The issue remains a challenge for states, especially as President Trump and other Republicans have alleged — without providing evidence — that tens of thousands, even millions, of noncitizens have illegally registered and voted in U.S. elections….

While claims of massive illegal voting by noncitizens have routinely been disproved, some noncitizens have ended up on the rolls, usually by accident.