The most important political event for the Central Valley in 2011 will be the April release of new California population figures by the U.S. Census Bureau. For the first time in our history, the state is growing no faster than the nation.

But more importantly, there has been a huge population shift within the state, virtually all of it from the coastal counties to the interior. The upshot will be more political power to the Central Valley and inland California because legislative and congressional districts will have to be adjusted to reflect the population changes.

The Rose Institute of State and Local Government at Claremont McKenna College in Claremont has analyzed these changes and estimates roughly a million people have moved from the Bay Area and coastal counties to the interior over the past decade, overpopulating existing districts inland and underpopulating districts along the coast. For instance, the institute estimates that California’s 3rd and 4th congressional districts, both in the Sacramento area and represented by Republican Reps. Dan Lungren and Tom McClintock respectively, are overpopulated by 88,000 and 100,000 people, while the district of former Democratic House Speaker Nancy Pelosi in San Francisco is underpopulated by 121,000 people.

When the populations of all congressional districts bordering the Bay Area are added together, they are short one full congressional district, and the inland area from the Oregon border down to about Bakersfield is overpopulated by at least one full district. This means the Bay Area will lose a seat in Congress and the Central Valley will gain a seat.

In past decades, this population shift might not have mattered that much because of the ability of politicians to gerrymander districts to keep favored incumbents in office. One can hardly imagine the Democrat-controlled Legislature producing a plan that did not have a seat for former Speaker Pelosi. But the Legislature is no longer drawing the districts; a nonpartisan commission is.

Passage of Proposition 11 in 2008 and Proposition 20 in 2010 took redistricting power away from the Legislature and gave it to the new 14-member Citizens Redistricting Commission that’s insulated from the Legislature. The commission will draw the lines according to strict criteria. That should lead to more rational districts that reward more political power to growing areas of California.

The Central Valley will be a big winner in this process because the districts will be more compact and reflect communities of interest. A new congressional district could emerge covering San Joaquin County and the southern Sacramento area. During the 2001 redistricting, the Stockton area was badly gerrymandered, and as a result it has no member of Congress, no state senator and fewer members of the Assembly than it deserves. The new commission is likely to rectify that.

Not only will the Central Valley gain clout in Washington, but it will also gain in Sacramento. One and possibly two Assembly districts must be moved from the Bay Area to the interior. One new district could emerge in the foothills east of Sacramento. The 4th Assembly district in Placer County and the mountain counties is overpopulated by 107,000 people.

The criteria that will guide the commission will also prohibit the elongated districts that currently run through the Sacramento region. No longer will the 15th Assembly District start in Walnut Creek and extend to parts of Elk Grove, and the 10th Assembly District will not run from Lodi to El Dorado Hills. These districts will be much more compact.

These new districts are also likely to be much more politically competitive than the gerrymandered districts we have now. All the Bay Area losses will come out of the Democrats’ hide; that’s because all the districts in the Bay Area are Democratic. The fact some of them will be moved inland may cost the Democrats some safe incumbents, but it does not necessarily mean Republican districts will emerge in their place.

Republicans have lost three Assembly districts in Sacramento and surrounding counties since 2008, most recently the 5th District formerly represented by Republican Roger Niello. Democrat Richard Pan won that district in 2010 in part because the GOP nominated a candidate too conservative on social issues.

Ten years ago, these suburban neighborhoods were generally Republican, but Democrats have made big gains over the past few years. Today, these areas are politically marginal. That means the new districts the Citizens Commission will draw in this area will most likely also be politically marginal. A congressional district encompassing San Joaquin and southern Sacramento counties certainly would be, as would a new state Senate district and any new Assembly districts in these neighborhoods.

The redistricting reforms the people enacted in 2008 and 2010 will have two major benefits for the Sacramento area and the Central Valley: They will create districts that reflect population growth, and they are likely to create more competitive and politically marginal districts than we have today.

Tony Quinn is co-editor of the California Target Book, a nonpartisan analysis of legislative and congressional elections.