Question: When did the group that worked on USRA 2-6-6-2 disband?

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: 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 3: 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 4: 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 5: New York, Susquehanna & Western Railroad ALCO Type S-2 Locomotive: New York, Susquehanna & Western Railroad ALCO Type S-2 Locomotive is located in Maywood, Bergen County, New Jersey, United States. The locomotive was and added to the National Register of Historic Places on March 19, 2010. The locomotive is located adjacent to the Maywood Station Museum and is owned by the volunteer, 501(C)3 non-profit Maywood Station Historical Committee. In keeping with Susquehanna numbering practice, 206 (being even numbered) was MU-able to other locomotives. 206 last operated in early June 1985 before having a lube oil pressure failure that damaged it's 539 Macintosh and Seymore prime mover. As the Susquehanna was phasing out the last of the Alco's in the mid 80's (selling off or scrapping the remaining RS-1's and 3's) 206 was never repaired but was stored and retired in 1986 when it was decided to retire instead of repair.
Document 6: 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 7: 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 8: 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 9: 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 10: 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 11: 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 12: 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 13: 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 14: 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 15: ALCO MRS-1: The ALCO MRS-1 is a type of diesel-electric locomotive built by the American Locomotive Company for the United States Army Transportation Corps. They were built with multigauge trucks and to a reduced loading gauge for service anywhere in the world in the event of war.
ground_truth: 1920
sub_queries: Who worked on USRA 2-6-6-2? Answer: United States Railroad Administration
Which year did United States Railroad Administration end? Answer: 1920