Genesis refers to the fertile Jordan plain in the account of Abraham and Lot. Later the river became particularly important as the eastern boundary Israel crossed when entering the Promised Land.
Joshua 3-4 describes the waters stopping while the Israelites crossed on dry ground. Twelve stones were taken from the river as a memorial of the event.
Elijah and Elisha crossed the Jordan shortly before Elijah was taken away. Elisha returned across the river after receiving Elijah's mantle. Naaman the Syrian later washed seven times in the Jordan at Elisha's instruction and was healed of his skin disease.
In the New Testament, John the Baptist conducted his ministry at the Jordan, calling people to repentance and baptizing them. Jesus came to John and was baptized in the river before beginning His public ministry.