The zero point is a street corner, not a landmark
Chicago's street numbering runs from one crossing in the Loop, and the rule is written into city law rather than being a local habit. The Municipal Code of Chicago sets out the base lines for street numbering: streets running north and south are numbered from Madison Street, with number 1 at the north line of Madison increasing northward and a separate series increasing southward from its south line, while streets running east and west are numbered from State Street, with number 1 at the east line of State increasing eastward and increasing westward from its west line.
Everything else follows from that. An address on a north-south street measures your distance north or south of Madison. An address on an east-west street measures your distance east or west of State. There is no separate downtown scheme to learn.
Reading an address before you go there
An address in Chicago carries three pieces of information: a direction, a number and a street name. Take 2100 N Halsted Street. The N tells you it is north of Madison; the 2100 tells you how far; Halsted tells you which north-south street. You now know roughly where it is relative to the Loop and relative to any other address in the city, without a map.
Numbers rise at a steady rate as you move away from the base lines, with major cross streets falling at regular intervals, and the widely used local rule of thumb is that the numbering runs to roughly eight hundred per mile. That ratio is a convention rather than a figure stated in the numbering ordinance itself, so treat it as an approximation for judging walking distance rather than a precise measure.
North Side, South Side, West Side
Chicago's shorthand for its own geography comes straight out of the grid. Everything north of Madison is the North Side, everything south of it the South Side, and everything inland from the Loop beyond the river is the West Side. There is no East Side in the same sense, because Lake Michigan occupies that direction, which is why address numbers running east stop quickly and numbers running west continue for many miles.
Those three terms describe direction from the same zero point, and they are also used as social and historical shorthand for very different parts of the city. Read them as compass directions when you are navigating and as neighbourhood language when you hear them in conversation, and do not assume the two meanings are interchangeable.
The L and the Loop
The L is Chicago's rapid transit network, named for the elevated structure that carries much of it, and it is organised by colour rather than by number. The Chicago Transit Authority operates eight rail routes serving 146 stations across 224.1 miles of track, in the colours Red, Blue, Brown, Green, Orange, Pink, Purple and Yellow.
The Loop is the elevated rectangle of track around the downtown core, and it gives the district its name. Several lines run around it rather than through it, and CTA notes that Orange Line trains operate clockwise on the Loop structure, which is the detail that catches visitors: the direction a train travels around the Loop, not just its colour, decides which side of downtown you are delivered to.
Two lines run all night. CTA's own route page describes the Red Line as 24-hour service between Howard on the North Side and 95th/Dan Ryan on the South Side via the downtown subway, and the Blue Line likewise runs 24 hours between O'Hare and Forest Park, also via a downtown subway rather than the elevated. Every other colour has an overnight gap, so a late plan should be built around Red or Blue.
Fares and tapping with a foreign card
Ventra, the CTA's fare system, is built on open payment standards, which means a contactless card issued by a bank outside the United States works directly at the turnstile. Ventra's own guidance on paying with contactless bankcards explains that a tap is processed as a credit-type transaction and that your card is authorised for up to USD 5.00 on first use as a pre-authorisation hold, with the actual fare charged once the system has calculated it, usually by the end of the business day.
The published CTA fare chart, effective 20 February 2023, sets the full L fare at USD 2.50 and the bus fare at USD 2.25, or USD 2.50 paying with cash on the bus, where no transfer is given. A transfer covering up to two additional rides within two hours is free. Entering at the O'Hare station carries a premium fare of USD 5.00, deducted on entry there only. Day passes are USD 5 for one day, USD 15 for three days and USD 20 for seven days, and a new Ventra Card costs USD 5, returned as transit value if you register it within 90 days.
Getting in from the airports
Chicago is one of the few cities with rail service to two major airports, and both journeys start inside the terminal. CTA's guidance for visitors arriving in Chicago puts the Blue Line from O'Hare to downtown at about 40 minutes and the Orange Line from Midway to downtown at about 25 minutes.
The O'Hare entry premium is the one thing worth planning around. If you already hold an unlimited day or multi-day pass, boarding at O'Hare carries no additional charge, so buying a pass before you travel rather than tapping pay-as-you-go can absorb that fare. Coming the other way, out to O'Hare, the premium does not apply.
Before your first ride
Work out your destination's grid coordinate before you leave: the direction letter and number will tell you which side of the Loop you are heading for and roughly how far, which makes it obvious whether the L, a bus or a walk is the sensible choice. Then decide how you are paying, because that decision is easier to make on the platform than at the turnstile.
Fares, timetables and service patterns change, and the fare chart above carries its own effective date. Check the current figures on the CTA fare page for your travel date, and check the L route status page before a late-night journey, since overnight service outside the Red and Blue lines is limited and weekend engineering work reroutes trains around parts of the Loop.