former Frisco headquarters in Springfield built in 1910 and now known as the Landmark Building, is an official City of Springfield counsel-approved landmark. The Frisco Bridge at Memphis was the first bridge over the Mississippi River south of St. Louis, and the third longest bridge in the world at the time of its dedication on May 12, 1892; it is now listed as an National Historic Civil Engineering Landmark. 4-4-0s Locomotives with 4-4-0 wheel arrangements, known as the "American" type because they were considered for many years to be the standard in American locomotives, originally served Frisco in great numbers. In July, 1903, the Frisco had 159 4-4-0's in service, built by twenty-five different companies. Frisco renumbered its units in that year, assigning the 4-4-0's either numbers between 1-299 (140 units), or 2200-series numbers (19 units). The oldest Frisco 4-4-0 locomotive was No. 47, built in 1869 by Hinkley Locomotive Works. The last serving 4-4-0's were retired in 1951. 4-6-0s Even more numerous on the Frisco were 4-6-0 “Ten-wheelers.” The first such engines entered the Frisco system in 1870. By 1903, Frisco had a fleet of 430 such locomotives, which were renumbered that year into seven class series, using 400, 500, 600, 700, 1100, 1400, and 2600-series numbers. The last 4-6-0's on the Frisco roster were the 1400 series, with the last engine to be retired from service being #1409, dismantled and sold for scrap in November, 1951. Doodlebugs Frisco-series 2100 equipment consisted of self-propelled rail motor-cars, mostly gas-electric models, with a few gas-mechanical models given 3000-series numbers. These railway vehicles were commonly known as “Doodlebugs” for their insect-like appearance and the slow speeds at which they would doddle or "doodle" down the tracks. These were used to service various low-volume branch lines in the Frisco organization. An initial order for ten was placed in 1910, with seven more arriving by 1913, putting Frisco in the forefront of gas-electric operation at that time. The initial batch, numbered 2100 to 2109, included nine baggage-coach combinations, as well as one baggage-mail-coach unit. Frisco's peak year for motor-car mileage was 1931, and its fleet at that time included twenty-three gas-electrics, five gas-mechanical cars, four trailer coaches, and six mail-baggage units. The final Frisco run of a Doodlebug was on November 8, 1953, when No. 2128 traveled from Ardmore, Oklahoma, for the four hour trip to Hugo, Oklahoma. Frisco Series 4300 and 4400 Two