BOARDMAN, Ohio — As if to drive home the point, a Trump campaign sign defiantly reminds passersby he won the presidency last month in this Mahoning Valley suburb of Youngstown, a once-dominant manufacturing town in the famed Steel Valley.

“It’s not as if we need any reminders,” said Paul Sracic, a political science professor at nearby Youngstown State University. “Trump has dominated the news cycle. It is almost like Barack Obama has disappeared and Trump is already president.