Boston & Albany 4-6-2 No. 561 was built by American Locomotive Company's Schenectady works in 1913 as one of six representatives of the railroad's class Km. With 75-inch drivers and 22x28-inch cylinders, the Km class had a boiler pressure of 200 p.s.i. These engines developed 28,520 pounds of tractive force and weighed 241,000 pounds. (For other dimensions see the commentary for No. 559 preceding.) As light, high-drivered passenger power the Km class found less work to do after World War II and were retired beginning in 1947. No. 561 and a companion held on till 1949, the last of the group to meet the torch. Carl Weber provided this photo, taken in Boston on September 14, 1946.