AUGUSTA — Maine’s jobless rate dropped to 3.9 percent in December, thanks in large part to sustained jobs in construction while the weather stayed warmer than usual.

The seasonally adjusted rate was down from 4.3 percent in November.

The state Labor Department said December’s jobless rate was lower than in December 1997, when the rate was 5.3 percent.

The comparable unemployment rate in New Hampshire and Vermont last month was 2.9 percent in both states.