The United States Watch Company is a historic factory complex at 260 Charles Street in Waltham, Massachusetts. Built in 1886 and enlarged in 1901, it represents one of the most successful spinoffs of the American Waltham Watch Company, Waltham's dominant watchmaker of the late 19th century. When the complex was listed on the National Register of Historic Places in 1989, it was the last watch factory left in the city.