A new federal memo could force hundreds of thousands of visa holders to leave the U.S.—and wait abroad—to apply for permanent residency.

Some face tighter filing rules, while many visa holders may need to leave the U.S. to complete green card applications overseas.

Immigrants and their advocates and lawyers are trying to interpret a new Trump administration rule that requires people to be in their native country to apply for a green card. By Christina Morales A ...