Question: What year saw the end of the administration that developed USRA Light Mountain?

full_context: Document 1: USRA 2-8-8-2: The USRA 2-8-8-2 was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. These locomotives were of 2-8-8-2 wheel arrangement in the Whyte notation, or (1'D)'D1' in UIC classification. A total of 106 locomotives were built to this plan for the USRA; postwar, it became a de facto standard design.
Document 2: USRA Light Mikado: The USRA Light Mikado was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard light freight locomotive of the USRA types, and was of 2-8-2 wheel arrangement in the Whyte notation, or 1′D1′ in UIC classification.
Document 3: USRA Light Pacific: The USRA Light Pacific was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard light passenger locomotive of the USRA types, and was 4-6-2 wheel arrangement in the Whyte notation, or 2′C1′ in UIC classification.
Document 4: USRA Light Mountain: The USRA Light Mountain was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard light freight locomotive of the USRA types, and was of 4-8-2 wheel arrangement in the Whyte notation, or 2′D1′ in UIC classification.
Document 5: USRA Heavy Mikado: The USRA Heavy Mikado was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration (USRA), the nationalized railroad system in the United States during World War I. These locomotives were of 2-8-2 wheel arrangement in the Whyte notation, or 1′D1′ in UIC classification. A total of 233 locomotives were built to this plan for the USRA; postwar, it became a "de facto" standard design, which was built to the total of 957 locomotives including the USRA originals and all subsequent copies.
Document 6: United States Railroad Administration: The United States Railroad Administration (USRA) was the name of the nationalized railroad system of the United States between December 28, 1917, and March 1st, 1920. It was possibly the largest American experiment with nationalization, and was undertaken against a background of war emergency.
Document 7: USRA 2-6-6-2: The USRA 2-6-6-2 was a standardized design of 2-6-6-2 Mallet locomotives developed by the United States Railroad Administration during World War I.
Document 8: USRA Heavy Santa Fe: The USRA Heavy Santa Fe was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. These locomotives were of 2-10-2 wheel arrangement in the Whyte notation, or 1′E1′ in UIC classification; this arrangement was commonly named "Santa Fe" in the United States. At the time, the Santa Fe was the largest non-articulated type in common use, primarily in slow drag freight duty in ore or coal service.
Document 9: USRA 0-6-0: The USRA 0-6-0 was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard light switcher of the USRA types, and was of 0-6-0 wheel arrangement in the Whyte notation, or "C" in UIC classification.
Document 10: USRA Heavy Mountain: The USRA Heavy Mountain was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard light freight locomotive of the USRA types, and was of 4-8-2 wheel arrangement in the Whyte notation, or 2′D1′ in UIC classification.
Document 11: USRA Heavy Pacific: The USRA Heavy Pacific was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard heavy passenger locomotive of the USRA types, and was 4-6-2 wheel arrangement in the Whyte notation, or 2′C1′ in UIC classification.
Document 12: USRA Light Santa Fe: The USRA Light Santa Fe was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. These locomotives were of 2-10-2 wheel arrangement in the Whyte notation, or 1′E1′ in UIC classification; this arrangement was commonly named "Santa Fe" in the United States. At the time, the Santa Fe was the largest non-articulated type in common use, primarily in slow drag freight duty in ore or coal service.
Document 13: Pacific 231: The popular interpretation of the piece is that it depicts a steam locomotive, an interpretation that is supported by the title of the piece alongside film versions. Honegger, however, insisted that he wrote it as an exercise in building momentum while the tempo of the piece slows. He originally titled it Mouvement Symphonique, only giving it the name Pacific 231, a class of steam locomotive designated in Whyte notation as a 4-6-2, with four pilot wheels, six driving wheels, and two trailing wheels (the French, who count axles rather than wheels when describing locomotives, call this arrangement 2-3-1) after it was finished.
Document 14: USRA 0-8-0: The USRA 0-8-0 was a USRA standard class of steam locomotive designed under the control of the United States Railroad Administration, the nationalized railroad system in the United States during World War I. This was the standard heavy switcher of the USRA types, and was of 0-8-0 wheel arrangement in the Whyte notation, or "D" in UIC classification.
Document 15: St. Louis–San Francisco 4003: St. Louis–San Francisco 4003 is a 2-8-2, Mikado type, standard gauge steam railway locomotive built by the American Locomotive Company in 1919 as a standard USRA Light Mikado for the Pennsylvania Railroad. The PRR, for unknown reasons, rejected 33 of 38 locomotives in the order. The United States Railroad Administration reassigned 23 of them (road numbers 4000-4007 and 4017-4031) to the St. Louis–San Francisco Railway (SLSF), also known as the "Frisco". The Frisco also received 10 sisters from the Indiana Harbor Belt Railroad (road numbers 4008-4016 and 4032), making 33 in all. She is now on display at the Fort Smith Trolley Museum in Fort Smith, Arkansas.
ground_truth: 1920
sub_queries: Who developed USRA Light Mountain? Answer: United States Railroad Administration
Which year did United States Railroad Administration end? Answer: 1920