The Providence and Worcester Railroad (P&W; reporting mark PW) is a Class II railroad operating 612 miles (985 km) of tracks in Rhode Island, Massachusetts, and Connecticut, as well as New York via trackage rights. The company was founded in 1844 to build a railroad between Providence, Rhode Island, and Worcester, Massachusetts, and ran its first trains in 1847. A successful railroad, the P&W subsequently expanded with a branch to East Providence, Rhode Island, and for a time leased two small Massachusetts railroads. Originally a single track, its busy mainline was double-tracked after a fatal 1853 collision in Valley Falls, Rhode Island.
The P&W operated independently until 1888, when the New York, Providence and Boston Railroad (NYP&B) leased it; four years later, the New York, New Haven and Hartford Railroad obtained the lease when it purchased the NYP&B. The P&W continued to exist as a company, as special rules protecting minority shareholders made it prohibitively expensive for the New Haven to purchase the company outright. The New Haven continued to lease the Providence and Worcester for 76 years, until the former was merged into Penn Central (PC) at the end of 1968.