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 pounds per square inch. 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.