Speed limit is 20mph even though it it a divided 4-lane street. There is a high school at the corner of Stumph and Gretna Blvds. but the speed limit stays at 2omph even after the school zone ends. My mother (of all people) got a speeding ticket for doing 30! (no leeway was given) well past the school zone and during the month of June when school was out. The scuttlebutt is "the reason for this speed zone is that many of Gretna’s prominent citizens live near this street and don’t like the traffic even though this is a main connecting street."