The preliminary unemployment rate for March is the lowest since 1976, when current record-keeping began.

The 2.7 rate of unemployment could be the lowest since 1957, when Eisenhower was in the White House, according to Glenn Mills, chief economist with the Maine Department of Labor.

The state’s monthly unemployment rate continues a streak of 28 consecutive months where rates have been below 4 percent. Such persistent low unemployment has been contributing to a tightening labor pool.

March’s rate is down slightly from February’s 2.9 percent, and well below March 2017’s rate of 3.3 percent.

The U.S. preliminary unemployment rate of 4.1 percent for March has been unchanged for six months; it is down from 4.7 percent one year ago. The New England average was 3.6 percent.

This story will be updated.