The Republican National Convention kicks off July 18 in Cleveland, the city’s first such event since 1936. That means about 50,000 visitors will be in town for the week — Republican National Committee staff, donors, lobbyists, journalists, delegates and alternates. The list goes on. Committee spokesman David O’Neil says it will be the second most credentialed event in the world in 2016, behind only the summer Olympics in Rio de Janeiro.

Suffice it to say, Cleveland is on...