average highway speed limit (mph)
The speed limit on a freeway in Idaho is 80 mph rural, 65 mph urban, and a 70 mph truck speed limit. Generally both 2- and 4-lane highways have 70 mph limits, and roads with traffic lights are posted at 60 mph or below.peed limits in the United States vary depending on jurisdiction, with 75 to 80 mph (120 to 130 km/h) common in the Western United States and 65 to 70 mph (105 to 115 km/h) common in the Eastern United States. States may also set special speed limits for trucks and night travel along with minimum speed limits.