HARRISBURG — Pennsylvania’s unemployment rate dropped in January to its lowest rate since 2008, but hiring remained flat.

The state Department of Labor and Industry said Pennsylvania’s unemployment rate fell four-tenths of a percentage point to 6.4 percent in January. Friday’s figures also included a downward revision to December’s unemployment rate, from 6.9 percent to 6.8 percent.

The drop continues a steady decline in Pennsylvania’s unemployment rate since it was at a post-recession high of 8.1 percent in September 2012. The national rate was 6.7 percent in January, after falling from a post-recession high of 10 percent in 2009.

A big contributor to the falling unemployment rate has been a drop in the size of Pennsylvania’s labor force, the number of people working or searching for work. Economists say not as many younger people are entering the labor force as more people retire, quit looking for work out of frustration or stop their job search for another reason.

Pennsylvania’s labor force shrank in January by 8,000, while the number of employed people rose by 15,000 and the number of unemployed fell by 23,000.

In a separate survey of employers, the department estimated that payrolls remained flat. With a slight downward revision from December’s figure, payrolls were slightly under 5.76 million jobs in January.