They gathered for a protest in Daley Plaza this afternoon.
Four years ago, former president Lech Kaczynski was traveling from Warsaw to Russia when the plane crashed near Smolensk.
96 people were killed, including Kaczynski and several government officials.
An investigation found weather conditions and pilot error were to blame, but some members of the Polish community say that's not true and want to know the real cause of the crash.
