President Trump on Wednesday floated the idea of issuing every American adult a $5,000 “dividend” check if his party kept control of the House and Senate in November — an extraordinary offer that would cost more than $1 trillion and likely would require congressional approval. “It will be called the Trump dividend,” he said at the Republican midterm convention in Dallas. He added a caveat: The money must be spent in the United States, though he did not say how the government could track where private citizens used the funds. He offered few additional details about the idea. How could...