High Quality Content by WIKIPEDIA articles! Interstate 781 (I-781) is an auxiliary Interstate Highway north of Watertown in Jefferson County, New York, in the United States. The route extends for 4.9 miles (7.9 km) from an interchange with I-81 in Pamelia to the main entrance of Fort Drum in Le Ray. It also has one intermediate interchange with U.S. Route 11 (US 11) just west of Fort Drum. I-781 is four lanes wide and serves as the principal travel corridor into and out of the post. The freeway is ceremoniously designated as the Paul Cerjan Memorial Highway in honor of Paul G. Cerjan, a late US Army Lieutenant General who oversaw a $1.2 billion expansion of Fort Drum in the 1980s.