That only 20 percent of registered voters braved the sunny weather to cast ballots in Pennsylvania on Tuesday is pitiful. Less than 15 percent of the commonwealth's voting-age populace is making decisions for the rest of us.

Yes, with the Republican presidential nomination process essentially over, there was no action at the top of the ticket. Still, each party had significant contests. Five Republicans were vying for the nomination to face Sen. Bob Casey in November. And Democrats had two serious candidates in Patrick Murphy and Kathleen Kane seeking to become the first of their party elected attorney general.

Yet just 20 percent turnout. We deserve the government we get.

Of course, there is one relatively simple solution that would immediately allow almost a million additional voters to cast ballots in future low-turnout primaries. I am talking about people already registered to vote. And what I propose requires no "Vote or Die" shock and awe, no game-changing political rock star. Of course, I realize the idea also has no political prospect for enactment.

I'm talking about open primaries.

As I have often noted, across the country and within the commonwealth, the political designation showing the most growth is neither "R" nor "D," but "I" — as in independent.

In five Gallup surveys in 2012, an average of 42 percent of Americans have identified themselves as political independents (compared with an average of 29.4 percent self-identifying as Democratic, and 27.4 percent as Republican), up from last year's 60-year high of 40 percent.

Here in Pennsylvania, independent voters fall under the heading "no affiliation" — the only classification on the rise. Over the last four years, the Republican Party has shrunk by 123,557 registrants (3.9 percent), while the state Democrats have lost 66,807 (1.6 percent). Even those who collectively make up the state's stable of minor parties — Libertarians, Greens, Constitutions, and others — have dropped by 90,196 (15.9 percent) since April 2008.

Over the same period, the number of independents has swelled by 165,867.

Trouble is, independent voters are barred from participating in primaries. Yes, they know that when they join those ranks. (Full disclosure: I am one of them.) But if we are serious about increasing voter participation, why not expand the pool to include this emerging group?

Because that change would require the support of the General Assembly, which is controlled by elected officials from the major parties. They have shown no willingness to imperil their electoral fortunes by opening them up to the unpredictable and unaffiliated.

Consider: Three years ago, State Rep. Eugene DePasquale (D., York), who is running for state auditor general, introduced legislation to allow Keystone State independents and third-party affiliates to vote in primaries. Then-Attorney General Tom Corbett (and his gubernatorial race opponent, Dan Onorato) expressed support. Yet the measure languishes in the State Government Committee.

DePasquale has told me that getting his fellow legislators to budge on the bill would mean convincing them not only that the move was right, but also that there's a political risk in sitting on their hands.

"If there was ever a time that it was clear we should be empowering moderate, independent voters it is now," he said last week in an e-mail message. "Unfortunately, there has been little progress on this in Harrisburg. If this is going to change, voters must let their elected officials know how they feel."

The consistent growth in the number of independent voters is evidence of the mounting political risk in continuing to disenfranchise these citizens.

But worse is the damage done to the country when we coddle a two-party system in which only the most liberal and conservative voters shape the fields each spring. Absent the tempering effect offered by political independents, candidates are forced to appeal to an ideologically rigid portion of the electorate to earn their spot on a November ballot.

The result?

The most ideologically partisan Congress in modern history. Politicos more interested in grandstanding than governing. Political posturing instead of progress.

Open primaries alone won't end that. But they will flood our state's primary electorate with more disparate perspectives and perhaps spare us from anemic turnout numbers like Tuesday's.

At a very basic level, the move would finally open a seat at the table for a burgeoning portion of the electorate that for too long has been excluded without justification.

Contact Michael Smerconish via www.smerconish.com. Read his columns at www.philly.com/smerconish.