According to data from the US BLS, the unemployment rate of Connecticut was 4% (sa) in April, 2018. Among all Connecticut counties, these 3 were among those with high unemployment rates (nsa): Hartford (4.1%), Windham (4%), and New Haven (3.9%).

On the hand, the following three counties were among those with low unemployment rates (nsa): Middlesex (3.1%), Tolland (3.2%), and Litchfield (3.5%).

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

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