Maine’s historically low unemployment rate ticked up slightly in May, but continues a 30-month streak of being below 4 percent, the longest on record.

May’s rate of 2.8 percent is up from the 2.7 rate of March and April, but well below May 2017’s rate of 3.4 percent.

The Maine Department of Labor, which released May’s rate Friday, said there are about 19,500 unemployed Mainers. That compares with more than 630,000 in the workforce.

The preliminary U.S. rate for May was 3.8 percent, little changed from April’s rate of 3.9 percent and May 2017’s rate of 4.3 percent.

New England’s average unemployment rate for the month remained at 3.6 percent. Estimates for other states were 2.7 percent in New Hampshire, 2.8 percent in Vermont, 3.5 percent in Massachusetts, 4.4 percent in Rhode Island, and 4.5 percent in Connecticut.

The extended low unemployment rate has created a tight labor pool that continues to vex employers. This spring the state revised employment laws and offered incentives to encourage the hiring of teenagers to help ease job vacancies, especially among seasonal tourism businesses.