The Major William Francis Deegan Expressway, locally known as 'The Deegan', is a limited-access highway in New York City. It runs from I-278 (in the form of the Bruckner Expressway where it comes off the Triborough Bridge) in the South to the Grand Concourse in the north where it connects to the Mosholu Parkway and continues northward. The Deegan itself comprises approximately 8.3 miles of multi-lane highway. It is a part of Interstate 87, which continues to the North and turns into the New York Thruway. The Deegan is one of the three primary north-south commuter feed roads for Manhattan, along with the Henry Hudson Parkway and the Harlem River Drive/FDR Drive. As such, it can become horribly clogged with traffic at the drop of a hat.

Because it is such a critical road, it is known for three things: first, traffic on it tends to move at unreasonable speeds until it is forced to slow down by dint of there not being free roadway available. I have beeen in what are essentially bumper-to-bumper traffic jams which are, as a whole, moving at approximately 70 miles per hour. Second, the road itself is very curvy, as it was built after the New York City area around it was already urbanized and because it follows the eastern shoreline of the Harlem River. In addition, it has been bodged to handle several major highway interchanges in very limited physical space, including a complex and compressed junction with the elevated Interstate 95 where it comes off the bridge from Manhattan. Third, because it is one of the busiest roads in the New York City metro area, it is in generally terrible condition despite constant maintenance, because in addition to having a massive heavyweight traffic load (to include all the truck traffic that cannot use the two Manhattan options) it is too critical a thoroughfare to close down for road work for more than very short periods.

William Francis Deegan (its namesake) was in the United States Army - he fought in World War I as a staff officer in the Artillery. Following that war, he entered the Army Corps of Engineers as a Major and spent many years building federal military installations in New York State. A long time New Yorker, he was very politically active in the New York City political machine, as well as being a founder of (and New York state commander of) the American Legion. He passed away following, and apparently due to complications from an appendectomy in 1932. The road now known as the Deegan was built from 1939 to 1956, and it was named after him. In 1957, it was incorporated in the Eisenhower Interstate System as part of Interstate 87.