In 1918, the Baltimore & Ohio was allocated one hundred USRA light “Mikados” with 63″ diameter drivers, which were fitted immediately with thicker tires to bring them up to the B&O 64″ diameter standard, reducing the starting tractive effort to 53,868 pounds. They were designated as class Q-3 and were assigned road numbers 4500 through 4599.
Today: #4500 is the only surviving B&O Mikado to exist:
#4500 is on display at the Baltimore & Ohio Railroad Museum in Baltimore, MD.
B&O Q3 Mikado set includes: (1) Engine, (1) Tender & (1) Caboose