Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_21564794_3 (began_in_st_louis INTEGER, league VARCHAR)
### Question:
What year did Negro American League join?
### Answer:
SELECT MIN(began_in_st_louis) FROM table_21564794_3 WHERE league = "Negro American league"