New Jersey's April unemployment rate dropped below 9 percent - to 8.7 percent - marking its lowest point in four years, the state's Department of Labor and Industry reported Thursday.

A gain of 4,100 private-sector jobs offset a loss of 800 public-sector jobs, including scores of Camden police officers laid off last month when a county force took over policing the city.

While New Jersey's rate has fallen, it still tops the nation's, which was 7.5 percent in April.

To the Christie administration, the report, coupled with another showing better-than-expected increases in revenues from income, corporate, and sales taxes, points to an economy on the upward track.

"April saw the largest 12-month gain in the number of employed residents that New Jersey has seen in seven years, with an increase of more than 60,000 compared to April 2012," said Charles Steindel, chief economist for the Department of Treasury.

State Treasurer Andrew Sidamon-Eristoff took the tax report as a sign that "New Jersey's diversified economy continues to grow stronger."

And, in a note to Statehouse reporters from Gov. Christie's spokesman: "Not since 1977 has there been such a steep drop in the unemployment rate in just two months. . . .

"Once again it's clear the economy is moving in the right direction," the spokesman wrote.

Not surprisingly in an election year, State Sen. Barbara Buono, the expected Democratic challenger for governor, had a different view.

"Gov. Christie's economy boasts an unemployment rate that is a point above the national average, declining wages, and 400,000 people still looking for work," she said in a statement.

"For three years, his primary job-creation program has been to subsidize corporations that move jobs within the state and prevent millionaires from paying their fair share."

The size of New Jersey's labor force increased by 31,200 over the year. Typically an increase in the labor force indicates increased confidence in the potential job market. However, over the last month, the size of the labor force declined by 4,400, perhaps a sign of some weakening.

The labor force consists of people who are employed or who actively searched for work during the month.

In April, the number of unemployed people dropped by 15,700 to 399,500.

Hiring in education and health boosted April's job numbers in New Jersey, with that sector expanding by 3,700 in April. Other growth came in leisure and hospitality, financial services, and trade, transportation, and utilities, which includes retailing.

Declining was the key sector of manufacturing, which dropped by 1,200 jobs. Business services fell by 4,700 jobs. Construction also fell, by 300 jobs, seasonally adjusted.

That means construction may have actually added jobs in April, but measured against norms expected for the spring construction season, hiring was not up to the mark.

Contact Jane Von Bergen at jvonbergen@phillynews.com, @JaneVonBergen on Twitter, or at 215-854-2769. Read her workplace blog at www.philly.com/jobbing.