Frederick County's jobless rate also rose - from 3 percent to 4.1 percent - in January.
Still, the jobless rates in both Washington and Frederick counties were 0.6 percent below their January 1997 levels.
The rise in unemployment was predicted based on seasonal expectations of post-holiday and weather-related layoffs, said Patrick Arnold, director of the Office of Labor Market Analysis and Information.
Those seasonal factors can be offset in a very strong growth period, but it's rare, Arnold said.
Many manufacturers shut down production temporarily due to a slack in demand following the holiday season, he said.
Often companies will have "vacation shutdowns," where they require employees to take all or part of their vacation time, in January, Arnold said.
Temporary shutdowns in manufacturing probably account for the bulk of the increase in unemployed private-sector workers in January, he said.
Layoffs are also expected in the construction industry during the winter months, when work usually slows down, Arnold said.
Semester breaks at colleges account for a significant portion of the increase in public-sector unemployment in January, he said.
In Washington County, 67,250 out of an available 71,156 workers were employed in January.
In Frederick County, 93,845 out of an available 97,810 workers had jobs.
The state and national jobless rates also jumped in January.
Maryland's statewide average rose from 4.5 percent to 5.1 percent. The state-wide jobless rate was 5.3 percent in January 1997.
The national average increased from 4.4 percent to 5.2 percent. The nation-wide jobless rate was 5.9 percent in January 1997.