Dominoes are falling around Maryland. Of the ten lawmakers that Marylanders sent to Congress, four are leaving their seats. U.S. Sen. Ben Cardin announced his retirement, as did Reps. John Sarbanes and Dutch Ruppersberger. Rep. David Trone isn’t running for reelection because he’s running for Cardin’s Senate seat. Just as Cardin’s retirement is creating another vacuum as Trone runs for the Senate seat, Ruppersberger’s retirement could create a follow-on vacancy as others attempt to climb the political ladder.