CREATE TABLE table_24468 ("Team" TEXT, "Sport" TEXT, "League" TEXT, "Established" FLOAT, "Began in St. Louis" FLOAT, "Venue" TEXT, "Championships in St. Louis" TEXT, "Left St. Louis" FLOAT)

What year did Negro American League join?
SELECT MIN("Began in St. Louis") FROM table_24468 WHERE "League" = 'Negro American League'
SELECT MIN("Began in St. Louis") FROM "table_24468" WHERE "League" = 'Negro American League'