This election is notable in many ways. For the first time since 1952, neither the president nor the vice president will be his party's presidential nominee. For the first time since 1960, a sitting U.S. senator will be elected president. And for the first time ever, if the Democrats win, the next president will be female or black.

We are also at a fork in the policy road, for any of the three major candidates would lead us in very different directions on major public policy issues, from spending and taxation on the one hand,...