From Chicago Union Station to O'Hare Airport
All Amtrak trains serving Chicago arrive at Union Station. The best way to travel between Union Station and the airport is by the CTA rail. Trains are fast and run frequently, and the entire journey (including all waiting and walking) takes approximately 1 hour 15 minutes. Beware that private shuttles run much less frequently than CTA trains do (about once an hour compared to every 10 minutes), and so on average you are not going to save much time by taking a shuttle despite paying at least 10 times as much as the train fare. Moreover, trains run at all times, and trains do not risk getting stuck in Chicago traffic. Unless you have a lot of heavy luggage, a train ride is a more sensible option in most cases. The two maps you will need for this journey are the Downtown Chicago map and the CTA rail map.
First of all, you need to get to the CTA station (the Clinton station on the Blue line). The Clinton station is located two blocks (300 m) south of Union Station (map). Exit Union Station to Clinton and walk south towards the highway. The entrances to the CTA station are located on Clinton underneath the highway overpass over the street. The entire walk takes about 5 minutes.
Now you are at the CTA station. The fare is $3. Buy a single-ride ticket from the farecard machines (cash, debit or credit cards). Pay your fare, pass through the turnstiles to the boarding platform, and board any Blue line train headed to O'Hare (check the destination signs on the arriving train). Travel to the O'Hare station and get off the train. The travel time from Clinton to O'Hare is 46 minutes; trains run every 5-10 minutes daily.
Finally, you need to get from the CTA station to your departure terminal. If your flight departs from any of the domestic terminals (Terminal 1, 2 or 3), simply follow the signs to that terminal. Upon exiting the rail station take the underpass to the right to Terminal 1, the underpass straight ahead to Terminal 2, or the underpass to the left to Terminal 3. The entire walk takes about 10 minutes. If your flight departs from the International terminal (Terminal 5), you will need to take the Airport Transit System (ATS) first. Upon exiting the rail station walk towards Terminal 3 (follow the underpass to the left), just before passing the first set of the glassy doors turn left again, follow the narrow tunnel until it ends, take an elevator up to Level 4, walk to the overpass in the parking building, take an escalator down to the ATS station, and travel by an automated train to Terminal 5. The entire trip takes about 15 minutes.
The total travel time from Union Station to O'Hare should be about 1 hour 15 minutes including all walking, waiting, and riding the train (about 1 hour 20 minutes if you are going to the International terminal).
The Blue line operates at all times, and so there is no last train to miss.
If you have any questions, please check the "Frequently Asked Questions" page first. If you carefully read all of the above, checked the FAQs, and still have a question, please feel free to contact me.
Reverse directions: from O'Hare Airport to Chicago Union Station