NASHVILLE (WRCB) – Tennessee labor officials say the unemployment rate in Tennessee increased slightly in May over the previous month.

Tennessee Commissioner of Labor & Workforce Development Karla Davis announced today Tennessee's unemployment rate for May was 9.7 percent, up slightly from the April revised rate of 9.6. The national unemployment rate for May 2011 was 9.1 percent, up from the April revised of 9.0 percent.

According to the household survey conducted by the Labor and Workforce Development department, the number of employed Tennesseans also increased by 78,500 from May 2010 to May 2011, or 2.8 percent. The U.S. employment growth rate for the same period was 0.3 percent.

"The slight increase in the unemployment rate is attributed to significant growth in the labor force," Commissioner Davis said. "It is not uncommon for the jobless rate to increase when an economy is improving. The rate can go up because workers are entering the labor force faster than the economy is creating jobs."

The labor force is defined as the employed and those unemployed actively looking for a job. It does not include the unemployed not trying to find work. As the economy begins to expand, the labor force begins to expand as previously discouraged workers look for employment.

"For the fifth month in a row, the labor force is at a record level as more and more jobseekers are optimistic about their possibilities for finding work. The number of employed Tennesseans is the highest since September 2008," Davis added.