Cheap flights from South Dakota to Illinois from $103

The cheapest month to fly to Illinois from South Dakota is in September. Flight prices, which tend to average around $246, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of September, then flying in January is also cheap. Prices for this month can be found on momondo for an average of $249.

The cheapest day to depart from South Dakota to Illinois is on a Saturday when prices can be found for as low as $399. Flights from South Dakota to Illinois on a Monday will generally be more expensive and average around $618. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

Our most recent data shows that the best time of day to fly to Illinois is at noon. Flights from South Dakota to Illinois during this time can be as low as $364. Flights in the afternoon are often more expensive with an average ticket price of $497.

Fly from Rapid City to Chicago O'Hare Intl for the best South Dakota - Illinois flight prices

You are more likely to see cheaper flights to Illinois from South Dakota when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $294 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from South Dakota for as low as $203 on momondo.

There are 4 cabin classes available to choose from on South Dakota to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Frontier, Delta, and American Airlines are the most popular carriers operating from South Dakota to Illinois

United Airlines, American Airlines and Denver Air Connection are the top three most popular airlines that fly to Illinois from South Dakota according to our data. United Airlines is the first choice among our users, with 66% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 3 different airlines that fly to Illinois on a routine basis, so you have a few additional options to choose from.

As of February 2026, there are 5 flights per day flying from South Dakota to Illinois. The most common time of day flights depart is 12:00PM, with 48% of flights taking off in the afternoon.

The number of flights available between South Dakota and Illinois is 37 per week as of February 2026. The most frequent departure day is Tue, with 35% of weekly flights leaving on this day.