There are six airlines offering flights to Chicago. The most direct route isn’t necessarily the cheapest – being flexible is key to finding the lowest airfare rates. For example, try searching by month to see the best time of the week to fly.
You can use the filters on your search to see more flights and find cheaper rates – Chicago has more than one airport. So if you don't need to fly into Chicago O'hare International Airport, it's worth checking your other options. The 6220 km flight usually takes about 12 hrs.
Flights from Birmingham to are usually most expensive during September. If you're planning on going to Chicago during this time, you could take a look at other airport options. Or you could try to get a last-minute bargain.