According to data from the US BLS, the unemployment rate of Connecticut was 4.3% (sa) in December, 2017. Among all Connecticut counties, these 3 were among those with high unemployment rates (nsa): Windham (4%), New Haven (3.9%), and Hartford (3.8%).

On the hand, the following three counties were among those with low unemployment rates (nsa): Middlesex (3.1%), Tolland (3.2%), and Litchfield (3.4%).

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

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