According to data from the US BLS, the unemployment rate of New Hampshire was 2.7% (sa) in March, 2018. Among all New Hampshire counties, these 3 were among those with high unemployment rates (nsa): Coos (4.2%), Belknap (3.3%), and Carroll (3.3%).

On the hand, the following three counties were among those with low unemployment rates (nsa): Grafton (2.5%), Sullivan (2.7%), and Merrimack (2.7%).

The chart and table below shows the unemployment rate (nsa) for each county.

You can see similar information by state for the United States.