Historian Michael Kazin, a distinguished scholar of the American left, says American politics are caught in "the long 1960s." For decades Congress has been unable to pass sweeping measures desired by the progressive left to fundamentally reform American capitalism. They simply don't have the votes. In fact, neither major party recently has dominated Congress the way, for instance, Democrats did during the New Deal era, with more than 70 seats in the Senate and a massive advantage in the House. Why a partisan stalemate has endured since the 1960s is a complicated problem to unpack, but the answer leads to today's congressional math. Throughout U.S. history, very few periods of one-party dominance have occurred, periods where great legislative activity was possible.