Connecticut State Route 27 is a north-south highway in New London Conty. It runs just over three miles in length. CT St Rt 27 passes through the following towns in New London County. Stonington Groton CT St Rt 27 is not multi-plexed in New London County. CT St Rt 27 intersects the following highways in New London County. U.S. Rt. 1, at Stonington. Interstate 95, at Stonington. Connecticut State Route 234, at Stonington. Connecticut State Route 184, at Groton.