Iowa Code § 321.315 : TRANSPORTATION — VEHICLES — MOTOR VEHICLES AND LAW OF THE ROAD —TURNING AND STARTING AND SIGNALS ON STOPPING AND TURNING — Signal continuous

A signal of intention to turn right or left shall be given continuously during not less than the last one hundred feet traveled by the vehicle before turning when the speed limit is forty-five miles per hour or less and a continuous signal during not less than the last three hundred feet when the speed limit is in excess of forty-five miles per hour.