Last 80 mph speed limit sign before this trap appears at the 8.5 mile marker southbound. Next speed limit sign is 1/2 mile or so before exit 4, showing 65 mph. No other warning of such a dramatic change. Officers sit in various locations on either side of this sign, (whether in the 80 zone or 65). Considering that this is a 4-mile zone to the SD/IA line, it can definitely be considered a speed trap. I received a summons in this area and will be fighting it.