 On the crossing of the Connecticut River, I-95/US 1 comes into Old Lyme, New London County and immediately narrows to three southbound lanes, as it reaches the interchange with Route 156, where US 1 exits the highway and the concurrency ends.The freeway reduces to four lanes and heads into a heavily forested area with little development around the highway, where it crosses the Duck River.The road crosses the Threemile River prior to crossing the Fourmile River, as it enters the town of East Lyme.