Hawai'i's seasonably adjusted unemployment rate continued its steady rise in May, hitting a four-year high of 3.5 percent, yet remaining well below the national average, according to the state Department of Labor and Industrial Relations.

May's unemployment rate was 0.2 of a percentage point higher than April's 3.3 percent and a full percentage point higher than in May 2007. The Labor Department said the increase was expected because of the recent closures of Aloha and ATA airlines, and Molokai Ranch.

In the days after the shutdown of the airlines, the Department of Business, Economic Development and Tourism projected that the unemployment rate could reach 3.9 percent because of the job losses. But labor officials cautioned that the average length of unemployment in Hawai'i is 14 weeks and it would take at least a couple of months before the full impact of the layoffs is felt.

The state's seasonably adjusted workforce in May was 663,350, compared with 650,250 a year earlier. This year's workforce number comprised 639,900 employed and 23,450 unemployed.

Darwin Ching, labor department director, said he was "optimistic" that the state will maintain its relatively high employment rate despite the continued downturn of the economy.

"It is a testament to our local economy that employers have been able to maintain our low unemployment rates over the course of several years," he said.

In another measure of employment, the state reported that seasonably adjusted nonfarm payroll jobs increased by 3,900 in May when compared with a month earlier, and grew by 3,800 jobs from May 2007, the labor department said.

The industries in the private sector that saw considerable job growth since May 2007 were in educational and health services, which saw an increase of 1,800 jobs, and construction, 700 more jobs.

Nationally, the seasonably adjusted unemployment rate jumped from 5 percent in April to 5.5 percent in May. In May 2007, the national unemployment rate was 4.5 percent.