Halfway through the U.S. primary election season, at least one thing is clear: Voters in states that hold closed party primaries are, as usual, losing out. More than 20 states hold primaries in which only registered party members are eligible to participate. In a battleground state or district, that process can produce competitive general elections between Democrats and Republicans. But in areas where one party dominates, which is most of the country, it often leaves voters stuck with a single candidate who lacks majority support and reflects the priorities of ideological interest groups more than those of average voters. Take New York City’s recent primaries. In a four-way race for a Manhattan State Assembly district, the results were so close — the two leading candidates each have about 27 percent of the vote — that a recount may be required. But whoever comes out on top will not face a runoff — or a Republican, since none is running, which is the case in many other races, too. When Republicans, independents and third-party members arrive at the polls in November, joined by m