Final answer:
The first time recorded that a black man and a woman cast a vote in the United States was after the Fifteenth Amendment was ratified in 1870, granting Black men the right to vote.
Step-by-step explanation:
The historic vote where the Corps of Discovery would winter before their return journey was made by a black man and a woman. The identities of these individuals were not specifically mentioned in the provided information. However, it is important to note that the first time recorded that a black man and a woman cast a vote in the United States was after the Fifteenth Amendment was ratified in 1870, granting Black men the right to vote.