Charles Ellicott Commentary 2 Samuel 19:18

"And there went over a ferry-boat to bring over the king`s household, and to do what he thought good. And Shimei the son of Gera fell down before the king, when he was come over the Jordan." — 2 Samuel 19:18 (ASV)

As he was come over. —Rather, as he was coming over, as he was about to cross. Shimei and Ziba met the king on the east of Jordan, and his crossing is not spoken of until 2 Samuel 19:31–40.