Final answer:
A radio broadcast on the day the United States went to war is a primary source.
Step-by-step explanation:
A radio broadcast on the day the United States went to war would generally be considered a primary source in the field of history. Primary sources are original sources of information from the time period being studied. They typically consist of first-hand accounts or direct evidence from the time period.
In the context of a radio broadcast, this would mean that the broadcast is a direct record of an event as it was happening. It would provide valuable insight into the attitudes, perspectives, and events surrounding the war at that specific time.
Examples of primary sources in history include diaries, letters, photographs, speeches, and newspapers from the time period of the event in question.
Learn more about Primary and secondary sources