Chicago Geography and Layout: Lake, River, Sides and the Street Grid

Chicago is laid out on a flat grid along the southwest shore of Lake Michigan, with the Chicago River splitting downtown into north, west and south. Every address is measured from one zero point, State and Madison streets in the Loop, and numbers climb by 800 per mile. Once you know those two rules, you can find almost any place in the city.

Feature	Key fact
Lakefront	About 28 miles along Lake Michigan, with 24 beaches
Chicago River	Main Stem, North Branch and South Branch, meeting at Wolf Point
River reversal	Water first flowed into the new Sanitary and Ship Canal on January 2, 1900
Address zero point	State Street (east–west baseline) and Madison Street (north–south baseline)
Numbers per mile	800 (8 standard blocks)
Even and odd sides	Even numbers on the west and north sides of a street; odd on the east and south
Grid adopted	Passed by City Council in 1908; took effect September 1, 1909
The Loop	Area inside the elevated tracks on Lake, Wabash, Van Buren and Wells
Community areas	77

Lake Michigan and the lakefront

Lake Michigan forms Chicago’s entire eastern edge. The city has about 28 miles of lakefront with 24 beaches and about 18.5 miles of lakefront bike paths, according to Choose Chicago.

Jean Baptiste Point DuSable Lake Shore Drive runs along much of the shore. The City Council voted 33–15 on June 25, 2021, to give the outer drive, from Hollywood Avenue in Edgewater to 67th Street in Woodlawn, its current name. Locals still often call it Lake Shore Drive or LSD.

The lake shapes local weather. In spring and early summer it cools a strip of land about a mile inland, which is why forecasters say “cooler by the lake.” In fall and early winter the effect reverses and the shore stays slightly warmer. More in our Chicago weather guide.

The Chicago River and its three branches

The Chicago River has three parts. The Main Stem runs about 1.5 miles west from the lake to Wolf Point. There the North Branch comes in from the northern suburbs and the South Branch heads south and southwest toward the canal.

Chicago has 38 movable bridges over the river today, down from a peak of 52. The Chicago Riverwalk has been built along the south bank of the Main Stem since the early 2000s. Each March the river is dyed green for St. Patrick’s Day, a tradition that started in 1961.

Why the river flows backward

The river originally drained into Lake Michigan, which is also the city’s drinking water source. To carry sewage away from the lake, the Sanitary District built the Chicago Sanitary and Ship Canal, more than 28 miles long and over 160 feet wide. Water first flowed into it on January 2, 1900, and the river has flowed away from the lake ever since.

The canal also linked the Great Lakes to the Mississippi River system for shipping. Locks and sluice gates at the river mouth, including the Chicago Harbor Lock, control flow and let boats pass between the river and the lake.

The sides of Chicago

Chicagoans describe the city by sides: the North Side, the South Side and the West Side, plus combinations like the Northwest Side, Southwest Side and Far South Side. Because the lake is the eastern edge, there is no general “East Side.” The three white bands on the city flag represent the North, West and South sides.

The river is the traditional dividing line. North of the Main Stem is the North Side, west of the branches is the West Side, and south of the Main Stem is the South Side. For official boundaries, the city uses 77 community areas; see community areas and our neighborhood guides.

The street grid and address system

Chicago’s address system was devised by Edward P. Brennan, who first brought the idea to the City Council in 1901. The council passed it in 1908, and it took effect on September 1, 1909. It replaced a patchwork in which numbers on parallel streets often did not line up.

How to read a Chicago address

Zero point: State Street divides east from west, and Madison Street divides north from south.
800 per mile: Numbers climb by 800 every mile, which is 8 standard blocks of 100 numbers each.
Major streets: Main arterial streets usually fall every half mile (every 400 numbers), with secondary streets in between.
Direction prefix: Every address carries N., S., E. or W., such as 1060 W. Addison St.
Even and odd: Even numbers are on the west and north sides of a street; odd numbers are on the east and south sides.

Address number	About how far from State or Madison
800	1 mile
1600	2 miles
2400	3 miles (just west of Western Avenue)
3200	4 miles (just west of Kedzie Avenue)
4000	5 miles

On the South Side, addresses match the numbered streets: 2200 S. State Street is at 22nd Street. Because the numbered streets are unevenly spaced between Madison and 31st Street, the first three mile marks fall at 12th, 22nd and 31st streets.

Diagonal streets

A scattering of diagonal streets cut across the grid, such as Clark Street and Ogden Avenue. Many are thought to follow early trails or are among the city’s oldest roads. Their addresses still follow the grid: each diagonal is numbered as either a north–south or an east–west street and carries the usual N., S., E. or W. prefix.

Downtown and the Loop

The Loop is Chicago’s central business district. Strictly, it is the rectangle inside the elevated tracks on Lake Street (north), Wabash Avenue (east), Van Buren Street (south) and Wells Street (west). In everyday speech it often means downtown between the river, Michigan Avenue and Congress Parkway.

The name likely began with an 1880s cable-car loop and stuck after the elevated Union Loop opened on September 6, 1897. The elevated loop is 1.79 miles long, and five ‘L’ lines use it: Brown, Green, Orange, Pink and Purple. See the CTA ‘L’ guide and the Loop neighborhood guide.

Neighborhoods ring the Loop: River North and Streeterville across the river to the north, the West Loop and Fulton Market to the west, and the South Loop to the south. Their guides are at River North, Streeterville, West Loop and South Loop.

Expressways

Expressway	Interstate
Kennedy	I-90/I-94
Dan Ryan	I-90/I-94
Edens	I-94
Eisenhower	I-290
Stevenson	I-55
Chicago Skyway	I-90 (toll)

Locals call expressways by name, not number. For driving tips, see driving and parking in Chicago.

Frequently asked questions

Where is the center of Chicago’s address grid?

State and Madison streets in the Loop is the zero point. State divides east from west, and Madison divides north from south.

How many blocks are in a mile in Chicago?

Eight standard blocks, or 800 address numbers, make a mile.

Does the Chicago River really flow backward?

Yes. Since the Sanitary and Ship Canal opened in January 1900, the river flows away from Lake Michigan toward the Mississippi River system.

What are the three branches of the Chicago River?

The Main Stem, the North Branch and the South Branch. They meet at Wolf Point.

What are the boundaries of the Loop?

The elevated tracks run on Lake Street, Wabash Avenue, Van Buren Street and Wells Street. The term often stretches to cover all of downtown.

Is there an East Side in Chicago?

Not in the usual sense, because Lake Michigan is the city’s eastern edge. Locals divide the city into the North, South and West sides.

Related guides

Sources

Last updated: October 31, 2026