AUGUSTA – After he completes his second four-year term as Maine’s governor this year, independent Angus King plans to pack an RV and head toward the sunset, fulfilling a promise to his family to tour the country together.

King, who is constitutionally barred from serving a third consecutive term, is among the five chief executives in the New England states who will be gone after the November elections.

And if Connecticut’s John Rowland loses his re-election bid, all six New England governors will be out their statehouse doors.

“There’s going to be a lot of starting over,” said King, and “a lack of institutional memory.”

Like King, Rhode Island Gov. Lincoln Almond is term-limited. Massachusetts’ acting Gov. Jane Swift decided not to run when it became clear Mitt Romney was going after her party’s nomination.

New Hampshire Gov. Jeanne Shaheen wants to be a U.S. senator, and Vermont’s veteran governor, Howard Dean, wants to be president.

The regional turnover is part of a larger picture showing 36 elections this year for governorships in the states, 20 of them open seats, according to the National Governors Association.

“We’re expecting that when the dust settles, 50 percent of our membership will change over,” said Peter Wiley, an NGA senior staffer and former King aide.

A regional political observer, Boston University professor Caryl Rivers, said the governors are leaving en masse as states gain political significance.

“Governorships are increasingly important now because states are the laboratories for democracy,” said Rivers. She cited as examples Wisconsin’s leadership in welfare reform and Massachusetts’ in prison issues.

In the Bay State, Swift succeeded fellow Republican Paul Cellucci when he quit the governorship to become U.S. ambassador to Canada in April 2001. Swift decided not to seek election to the office herself, leaving Romney unopposed in the Sept. 17 GOP primary.

The four Democratic gubernatorial aspirants are former state Sen. Warren Tolman, state Treasurer Shannon O’Brien, former U.S. Labor Secretary Robert Reich and Massachusetts Senate President Tom Birmingham. Two third-party candidates are also running.