As part of a slowly improving employment situation, February saw 400 more people working in San Luis Obispo County than in January, according to data from the state and a firm that tracks the local economy.

Even while the labor force grew, the addition of 499 people to local unemployment rolls in February interrupted a four-month improvement trend that saw the jobless ranks shrink by hundreds, according to seasonally adjusted data from Beacon Economics.

Last month, 11,753 people in San Luis Obispo County reported they were unemployed. While the local unemployment rate is still nowhere near the pre-recession record low, thousands more have found work since the depth of the economic downturn.

Meanwhile, a seasonally adjusted 127,400 people were employed locally during February, according to Southern California-based Beacon’s analysis of state data.

That’s about 5,900 more people employed than the August 2009 trough of 121,500 working locally.

Seasonal adjustment of jobs data smoothes out traditional patterns of month-to-month variations — such as increased retail hiring during the winter holidays and summer furloughs of some workers in education — making month-to-month comparisons possible.

Unadjusted state employment data over the past year also point to an improving jobs market for San Luis Obispo County.

Construction and related fields have posted the second-biggest percentage gains of any sector locally, gaining about 300 jobs — 7.9 percent — since November, with about 4,100 employed during February.

The top-performing arts and entertainment sector posted a 9.1 percent gain of about 100 jobs during the same period, with about 1,200 people working locally in those fields — a smaller segment of the local economy. The U.S. Bureau of Labor Statistics describes that as a relatively low-wage sector that heavily employs young workers, and includes jobs in theater, museums and other leisure-time activities.

A few sectors posted modest job losses in San Luis Obispo County since November, with the nearly flat local government and finance, and insurance sectors being the worst performing during that three-month period.

Overall, the local economy has seen employment growth for eight of the past 12 months, according to state and Beacon data.

Even so, the unemployment rate for San Luis Obispo County grew to 8.4 percent in February, compared to 8.1 percent in January and 9.4 percent in February 2011, according to Beacon data.

That’s partly because the local labor force grew by 900 — about 400 more than the number of additional people employed during February.

The Bureau of Labor Statistics defines the labor force as people who are working or who are actively looking for work.

Economists calculate the unemployment rate by dividing the number of people who report they are unemployed by the number in the labor force.

That rate peaked locally at a seasonally adjusted 10.4 percent in April 2010, according to Beacon’s analysis of state data.

That contrasts to last decade’s lows of 3.7 percent unemployment in November 2006 and May 2007.

The number of people unemployed locally peaked at a seasonally adjusted 14,200 in February and November of 2010.