The drive to make Washington, D.C., a state has been a favorite of some Democrats for years. Why wouldn't it be? If enacted, a new state, formed from deepest-blue D.C., would create two new Democratic senators and one new Democratic member of the House. For a Democrat, what's not to like? But while there have been lots of D.C. statehood bills over the years, the issue has been voted on only once before. In 1993, it failed badly in the House, losing 277 to 153. Back then, moderate Democrats put their judgment before partisan interest, splitting on whether statehood was...