Cheap flights from Portland to Illinois from $106

The cheapest month to fly to Illinois from Portland is in January. Flight prices, which tend to average around $237, 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 January, then flying in August is also cheap. Prices for this month can be found on momondo for an average of $288.

The cheapest day to depart from Portland to Illinois is on a Friday when prices can be found for as low as $422. Flights from Portland to Illinois on a Monday will generally be more expensive and average around $526. 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 in the afternoon. Flights from Portland to Illinois during this time can be as low as $302. Flights in the morning are often more expensive with an average ticket price of $468.

Fly from Portland to Chicago O'Hare Intl for the best Portland - Illinois flight prices

You are more likely to see cheaper flights to Illinois from Portland when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $338 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from Portland for as low as $270 on momondo.

There are 4 cabin classes available to choose from on Portland 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 Alaska Airlines are the most popular carriers operating from Portland to Illinois

United Airlines, American Airlines and Alaska Airlines are the top three most popular airlines that fly to Illinois from Portland according to our data. United Airlines is the first choice among our users, with 41% of people opting to fly with this airline when traveling to Illinois. Keep in mind that there are 8 different airlines that fly to Illinois on a routine basis, so you have a few additional options to choose from.

As of March 2026, there are 21 flights per day flying from Portland to Illinois. The most common time of day flights depart is 11:00AM, with 70% of flights taking off at noon.

The number of flights available between Portland and Illinois is 150 per week as of March 2026. The most frequent departure day is Wed, with 17% of weekly flights leaving on this day.