Speed limits on some rural highways in South Dakota will increase in about three weeks.

The South Dakota Transportation Commission voted last month to raise the speed limit to 70 mph on five stretches of divided four-lane highways. The Legislature’s Rules Review Committee gave the final OK to the faster speeds Sept. 20.

Highways affected are:

• U.S. 83 between Pierre and Interstate 90;
• U.S. 12 between Aberdeen and Interstate 29;
• state Highway 37 between Mitchell and Huron;
• state Highway 50 from Yankton and Vermillion; and
• U.S. 281 between Aberdeen and state Highway 20.

Speed limits on those roads are now 65 mph.

South Dakota legislators approved a bill this year allowing the commission to decide if it’s safe to permit drivers to travel faster on four-lane state highways that are not part of the federal interstate system.

The speed limit on I-90 and I-29 in the state is 75 mph, but reduced to 65 mph through cities and towns.

In return for higher limits, anyone exceeding 70 mph on the affected stretches would be subject to a $200 fine and/or 30 days in jail.