The Arborway consists of a four-lane, divided parkway and a two-lane residential street in the Jamaica Plain neighborhood of Boston, Massachusetts, United States.

The roadway once continued through Forest Hills to the edge of Franklin Park, but now ends at the South Street border of the Arboretum.

The entire roadway is signed as Massachusetts Route 203, which continues along the parkway as Morton Street.

Named Monsignor William J. Casey Overpass in honor of a Depression-era priest of St. Thomas Aquinas Church in Jamaica Plain, the overpass was opened in November 1953 to allow the increasing automobile traffic of the day to bypass the north-south traffic on Washington Street, South Street, and Hyde Park Avenue.

[4] The Massachusetts Department of Transportation determined the overpass "structurally deficient" in 2010 and started work on replacing it with an at-grade roadway.