Q: Context: In January 1937, the Congress passed a joint resolution outlawing the arms trade with Spain. The Neutrality Act of 1937 was passed in May and included the provisions of the earlier acts, this time without expiration date, and extended them to cover civil wars as well. Furthermore, U.S. ships were prohibited from transporting any passengers or articles to belligerents, and U.S. citizens were forbidden from traveling on ships of belligerent nations.

Question: when was the neutrality act of 1937 passed?
Let's give stream of consciousness below
The relevant sentence in the passage is: The Neutrality Act of 1937 was passed in May and included the provisions of the earlier acts, this time without expiration date, and extended them to cover civil wars as well. So the answer is in May.