traffic on the West Boston Bridge, Massachussets, a century ago

Trolleys and an occasional 'horseless carriage', otherwise horse carriages. The Cambridge Subway (Red Line) tracks on the bridge have yet to be connected to anything.  The bridge itself, often called the "Salt-and-Pepper-Shaker Bridge", was opened in 1906 and is 1,768 feet (539 metres) long between the abutments and 105 ft (32 metres) wide.