Whether you're in the state with the slowest speed limit, or the one with the fastest speed limit sign, odds are you'll also find yourself passing through speed limited school zones. But when the heat of summer is in the air, you might wonder if school zone speed limits apply when school's out. A school zone sign does not automatically stop mattering just because classes are out for the summer. In many places, the key detail is what the sign actually says: some school zone limits apply only during posted school hours, some are active only when flashing lights are on, and others remain in effect whenever the roadway is legally designated as a school zone. That distinction matters because "school zone" is not always the same as "school in session."