Every year since the 2000 Census, an average of 2,424 people moved to the Big Island; while Oahu saw a net loss of 2,742 people moving away, according to an analysis of Census Bureau data by the state Department of Business, Economic Development and Tourism.

That's the main reason why the Big Island's population grew 1.9 percent last year, while Honolulu's population only grew by only 0.5 percent. Maui and Kauai increased 1.5 percent.

Since 1990, Oahu's share of the state's population has gone from 75.5 percent to 70.3 percent last year, and there's no reason to believe the demographic shift will change course, said Eugene Tian, a state research and statistics officer who prepared the analysis.

That population shift is changing local politics and could mean a change in the balance of power between Honolulu, still the main population center, and the faster-growing neighbor islands, political observers said.

Because Oahu's net population growth is mostly due to births and foreign immigration, groups which do not vote, the shift in the numbers of eligible voters is likely to be greater than the overall population changes.

Hawaii state Democratic Party Chairman Brian Schatz said the Big Island and Maui are likely to gain state House seats after the 2010 Census when state House and Senate districts and the 1st and 2nd Congressional District lines are redrawn to reflect population changes.

“;It's going to be a slight shift in the balance of power,”; Schatz said. With the population growth, however, the neighbor islands are facing similar problems to Oahu.

“;What were traditionally Oahu issues are now important to neighbor island residents, issues like traffic and urbanization,”; he said. “;Certainly in Maui, Kona and to some extent Kapaa, traffic is one of the overriding concerns.”;

Hawaii Republican Party Chairman Willes Lee said the changes could benefit the GOP, which he said has shown some strength in areas of high growth like Ewa, Lahaina, Kihei and Kona.

“;We think it (neighbor island population growth) is not just new people, but folks who share our values,”; Lee said.

Neighbor islanders also tend to vote in slightly higher numbers than the population would indicate and their share of the vote is rising, according to state election returns.

About 32 percent of the votes cast—nearly one out of three votes—in last year's presidential election were from the neighbor islands compared to about 30 percent in 2000.

“;We've been observing this pattern for a long, long time,”; said University of Hawaii political science professor Ira Rohter.

Rohter said the 1998 elections provided the first glimpse into how changing demographics is changing local politics.

In that election, former Maui Mayor Linda Lingle, a Republican, won a significant percentage of neighbor island votes.

“;It used to be the neighbor islands were solidly Democrat,”; Rohter said.

Lingle came back to win in 2002 and again in 2006, although her victories did not necessarily translate into Republican Party gains in the state Legislature.