The federal Highway Trust Fund, historically, is a fund that the government can’t be trusted to spend on federal highways. Unfortunately, Senator Bob Corker (R., Tenn.) is proposing to put more money in it by raising the federal gasoline tax, a proposal he’s concocted with Senator Chris Murphy (D., Conn.). Corker’s idea is bad policy and bad politics. The politics: Gas prices are rising rapidly, taxes on fuel are regressive, and Americans, rightly, really don’t like when you raise any kind of tax at all. There’s no pressing policy reason to increase the tax. The trust fund has plenty of...