There are five direct and indirect flights connecting Portland Oregon and Chicago every week, with the journey taking 4 hrs on average. Scroll through your results to compare flight times and prices
Or, if you're fairly flexible on dates, try to get a last minute-deal by regularly checking the Netflights website.
If you're not sure who to fly with from Portland Oregon, you might like to know that Alaska Airlines is the most popular airline for this route.
But if you can't find one which is right for you, try looking at flights to other cities in the USA to check out some other options.