In 1937 the US Federal Reserve tightened monetary policy substantially.

True: historical records show that the Federal Reserve tightened substantially in 1936–1937, for example by raising reserve requirements (doubling them in steps from August 1936 to May 1937), along with Treasury gold sterilization, which contributed to the 1937–38 recession. Mostly true: there was significant tightening, but its timing or form differs slightly (for example it began in 1936, or partly came from Treasury rather than the Fed). Mostly false: there was only minor Fed tightening in 1937, with the main tightening done by others. False: the Fed did not tighten in or around 1937.

Set before the research began.

1. E1 Navigating Constraints: The Evolution of Federal Reserve Monetary Policy, 1935-59 Board of Governors of the Federal Reserve System (FEDS Working Paper 2014-44), authors Mark A. Carlson and David C. Wheelock · 9 June 2014

   “To reduce excess reserves, the Board increased reserve requirements in three steps during 1936-37 that in sum doubled all required reserve ratios and brought them to the maximums allowed by law.”

2. E2 Navigating Constraints: The Evolution of Federal Reserve Monetary Policy, 1935-59 Board of Governors of the Federal Reserve System (FEDS Working Paper 2014-44), authors Mark A. Carlson and David C. Wheelock · 9 June 2014

   “In December 1936, the Treasury Department began to sterilize gold inflows to prevent them from further increasing bank reserves.”

3. E3 Navigating Constraints: The Evolution of Federal Reserve Monetary Policy, 1935-59 Board of Governors of the Federal Reserve System (FEDS Working Paper 2014-44), authors Mark A. Carlson and David C. Wheelock · 9 June 2014

   “The Fed stressed that the increases in reserve requirements (and gold sterilization) “did not reflect changes in Federal Reserve credit policy, which continued to be directed toward monetary ease.”

4. E4 Navigating Constraints: The Evolution of Federal Reserve Monetary Policy, 1935-59 Board of Governors of the Federal Reserve System (FEDS Working Paper 2014-44), authors Mark A. Carlson and David C. Wheelock · 9 June 2014

   “Friedman and Schwartz (1963) argue that the action was an important cause of the recession. They contend that banks held excess reserves as a precaution against bank runs, and that banks reduced credit supply in an effort to rebuild their excess reserves after reserve requirements were increased.”

A Federal Reserve staff paper [E1] says the Board raised reserve requirements in three steps during 1936-37. Together the increases doubled all required reserve ratios to the legal maximums. The same paper [E2] reports that the Treasury began sterilizing gold inflows in December 1936. It also cites Friedman and Schwartz's view that the reserve requirement increase was an important cause of the recession [E4]. The Fed said at the time that its credit policy was still aimed at ease [E3], but the doubling of reserve requirements alongside gold sterilization matches the criteria's description of substantial tightening in 1936–37.