In divided times, these families offer a refreshing and inspiring story. Meet the Gates and Mitchell families, suburban Pittsburgh residents. On one side, the Mitchells are Democrats and support Joe Biden. The Gateses, however, are lifelong Republicans and hope for a second term for President Trump. Troubled by the national discourse, they decided to use signs to ‘send a message’ of civility. Clare Ansberry tells their peculiar story for The Wall Street Journal.