WASHINGTON — The sharing economy is all the rage. People are sharing homes and cars, books and tools. Why not congressional districts?

Republicans and Democrats sink millions of dollars into four of races that regularly flip from one party to the other. Over the last four election cycles, New Hampshire’s 1st District and Texas’ 23rd District have changed hands three times and New York’s 24th District has flipped all four. Illinois’ 10th District flipped back and forth in 2012 and 2014 and could do it again in 2016.

If party strategists would agree to trade those seats every two years without contesting them, it would free up money in order to expand the House playing field and allow the parties to target other races.

From 2008 to 2014, the party committees and outside groups spent more than $71 million on those four seats alone, according to the Center for Responsive Politics.

The parties and outside groups spent nearly $21.8 million over the last four cycles in Illinois-10 (which is covered by the Chicago media market), $20.6 million in New Hampshire-1, $16.6 million in Texas-23, and $12.2 million in New York-24 (which was the 25th District until the 2012 elections).

“Timeshare districts make a lot of sense,” quipped one veteran Democratic strategist. “Democrats get them in the presidential election cycles. Republicans have a turn in the zombie off-years.”

“The Republican and Democratic members could even split rent and office resources,” said the strategist, who was granted anonymity to think outside the box and maybe be the first person to introduce hoteling for congressional staff. “And with a gentleman’s agreement – they all could stop raising campaign money, altogether. It’s really a win-win-win.”

THERE’S ALWAYS HOPE

Of course, the parties may not agree to a ceasefire because there is always hope that a flipping district will turn safe.

Indiana’s 9th District switched party hands three times in four elections from 2004 to 2010, partially including the series of four races when Democrat Baron Hill faced off against Republican Mike Sodrel. In 2010, Republican Todd Young defeated Hill and Democrats didn’t put forth much of an effort in 2012 and 2014 as President Obama’s popularity plummeted in the region. Even though Young is leaving the seat to run for the Senate, it’s not likely to be a hotly contested general election next year.

But it doesn’t look like any of the first four districts are going to be safe any time soon. Under the status quo mentality of challenging in competitive seats, all four seats are at some risk of flipping back again in 2016.

In Illinois-10, former Democratic Rep. Brad Schneider is back for a rematch after losing to Republican Robert Dold in 2014. Schneider defeated Dold in 2012.

In New Hampshire-1, former Rep. Carol Shea-Porter filed to run against Republican Rep. Frank Guinta. Guinta defeated Shea-Porter in 2014. Shea-Porter defeated Guinta in 2012. Guinta defeated Shea-Porter in 2010. Shea-Porter defeated Republican Jeb Bradley in 2006 and 2008.

So while redistricting reform gets all the attention in attempts to broaden the House playing field, timeshare districts should be part of the conversation as well. Or not.