The U.S. Supreme Court's preliminary approval of President Donald Trump's restrictions on mail-in voting has already thrown into uncertainty the method that nearly one-third of the country uses to vote — even if it may not lead to a single procedural change during the November midterms.

The U.S. Postal Service is issuing a new regulation limiting mail ballots in November's election, but it won't go into effect unless the U.S. Supreme Court allows it

The Supreme Court is siding with the Trump administration in a case over President Donald Trump’s executive order restricting mail-in voting, though it remains unclear how much…