L.A. County’s unemployment rate fell to 4.6 percent in March, the lowest level in at least 30 years, state figures released Friday show.

The unemployment rate fell from a revised 4.8 percent in February and was down from 5.4 percent a year ago, according to the state Employment Development Department.

The 4.6 percent figure for March, which is adjusted for seasonal factors, is lower than any of the previous unemployment rates recorded during the last three employment boom cycles, going back to 1989, according to online EDD records. The previous low of 4.7 percent was reached on several occasions. The seasonally unadjusted figure of 4.3 percent for March was tied only once, back in October 2006.

What’s more, the unemployment rate fell even as the county’s labor force grew by 15,000 to 5,082,000, thanks to the fact that 24,000 more county residents reported they were working in March than had reported in February.

“This is a good sign and indicates that even as the local economy is now very strong and nearing full employment, there is a little more room to grow,” said David Smith, associate professor of economics at the Pepperdine Graziadio School of Business and Management.

The county’s two largest cities, Los Angeles and Long Beach, reported unemployment rates of 4.6 percent and 4.7 percent respectively.

But Smith noted that other cities in the county, including Compton and East Los Angeles, still had unemployment rates topping six percent. “These areas still have room for improvement,” he said.

Statewide, the March unemployment rate was 4.9 percent, while the national rate was 4.5 percent, a smidgeon below the Los Angeles level.

Turning to the closely watched payroll jobs front, the county added 16,000 nonfarm payroll jobs to reach 4,439,900. The largest gains were in health care/social assistance (up 5,300) and local public education (up 4,900).

Some of this extra hiring – particularly in education – may be due to seasonal factors. When the EDD adjusted for those seasonal factors, the number of payroll jobs in the county actually fell by 9,000 in March.

The biggest drop in payroll jobs in March was in motion picture/sound recording, which shed 6,800 jobs. The sector also lost 5,000 jobs between March of last year and this March. These jobs losses have come in spite of production returning to the region as the result of higher state film tax credits and could indicate a continuing problem with runaway production. Also, better digital technology could be reducing the need for film production workers.

On a broader scale, the county gained 84,000 payroll jobs over the past 12 months for a growth rate of 1.9 percent, slightly better than the growth rates the county has been seeing recently. Healthcare/social assistance again led the way, adding 26,000 jobs, followed by food service (up 13,500) and professional/scientific/technical services (up 9,500).

Manufacturing continued on its long-term job decline, shedding 6,000 jobs over the past 12 months as automation and offshoring continued to take their toll.

Public policy and energy reporter Howard Fine can be reached at [email protected]. Follow him on Twitter @howardafine.