The following speed limits are established in Iowa Code § 321.285 and any speed in excess thereof is unlawful unless specifically designated otherwise in this chapter as a special speed zone:
(A) Business District: 20 mph;
(Iowa Code § 321.285(1))
(B) Residence or School District: 25 mph;
(Iowa Code § 321.285(2))
(C) Suburban District: 45 mph;
(Iowa Code § 321.285(3))
(D) All vehicular traffic, notwithstanding any other speed restrictions: 55 mph;
(Iowa Code § 321.285(4))
(E) Secondary roads: reasonable and proper speeds, but not greater than 55 mph at any time between sunrise and sunset, and not greater than 50 mph at any time between sunset and sunrise, unless the secondary roads are surfaced with concrete or asphalt or a combination of both, in which case the speed limits shall be the same as provided in division (D) above; and
(Iowa Code § 321.285(5))
(F) Fully controlled access, divided, multi-laned highways, notwithstanding any other speed restrictions: 65 mph.
(Iowa Code § 321.285(6))
(1999 Code, § 63.02) Penalty, see § 10.99