Located in northeastern Illinois at the southwestern tip of Lake Michigan,
Chicago's official geographic coordinates are
41°53′0″N, 87°39′0″W. It
sits on the continental divide at the site of the Chicago Portage, connecting
the Mississippi River and the Great Lakes watersheds. The city lies beside Lake
Michigan and two rivers: the Chicago River in downtown and the Calumet River in
the industrial far South Side, entirely or partially flow through Chicago. The
Chicago Sanitary and Ship Canal connects the Chicago River with the Des Plaines
River, which runs to the west of the city.
When Chicago was founded in the 1830s, most of the early building began
around the mouth of the Chicago River. According to the U.S. Census Bureau,
Chicago has a total area of 234.0 square miles (606.1 km²), of which 227.1
square miles (588.3 km²) is land and 6.9 square miles (17.8 km²) is water. The
total area is 2.94% water.
The city has been built on relatively flat land; the average elevation of
land is 579 feet (176 m) above sea level. The lowest points are along the lake
shore at 577 feet (176 m), while the highest point at 735 feet (224 m) is in the
landfill on the city's far south side (41°39′18″N,87°34′44″W).
Since the first recorded earthquake in 1804, Chicago has occasionally
experienced earthquakes. More recently, an earthquake with an epicenter in
Ottawa, Illinois, registering about 4.3 on the Richter scale shook some
buildings in Chicago on June 28, 2004. This earthquake sparked worries that the
New Madrid fault might become active again. An earthquake of 6 or higher in the
Missouri Fault might cause moderate to high damage in Chicago.
The city’s urban context is organized within a grid pattern. The pattern is
modified by the shoreline, the three branches of the Chicago River, the system
of active/inactive rail lines, several diagonal streets (including Clybourn
Street, Milwaukee, Lincoln, Elston, Archer, and Ogden Avenues), the expressways,
and hundreds of bridges and viaducts. In addition, the baselines for numbering
streets and buildings are State Street (for east-west numbering) and Madison
(for north-south numbering). Street numbers begin at "1" at the baselines and
run numerically in directions indicated to the city limits, with N, S, E, and W
indicating directions. Chicago is divided into one-mile sections which ideally
contain eight blocks to the mile, with each block's addresses ideally occupying
a 100-number range. Even-numbered addresses are on the north and west sides of
streets; odd-numbered address are on the south and east sides.
Since the first steel-framed high-rise building of the world was constructed
in the city in 1885, Chicago has been known for the skyscraper. Today, many
high-rise buildings are located in the downtown area, notably in the Loop and
along the lakefront and the Chicago River. The three tallest buildings are the
Sears Tower (also the tallest building in North America), the Aon Center, and
the John Hancock Center. The rest of the city consists of low-rise buildings and
single-family homes. There are clusters of industrialized areas, including the
lakefront near the Indiana border, the area south of Midway Airport, and the
banks of the Chicago Sanitary and Ship Canal.
Future building sites that will contribute to Chicago's skyline include
Waterview Tower, 400 North Lake Shore Drive, and the Trump International Hotel
Along Lake Shore Drive, parks line the lakefront. The most notable of these
parks are Grant Park and Millenium Park, which border the east end of the Loop,
Lincoln Park on the north side, and Jackson Park in the Hyde Park neighborhood
on the south side. Interspersed within this system of parks are 31 beaches, a
zoo and several bird sanctuaries, McCormick Place Convention Center, Navy Pier,
Soldier Field, the Museum Campus, and a water treatment plant.
Pushed along by the national real estate boom in recent years, Chicago has
seen an unprecedented surge in skyscraper construction, most notably in the area
directly south (South Loop) and north (River North) of the Loop. This has been
accompanied by a rapid gentrification of many parts of the city, as once-dormant
areas become "hip" neighborhoods replete with an increased level of commercial
services. An example is the west-side neighborhood Wicker Park.
Chicago, like much of the Midwest, has a climate that is prone to extreme,
often volatile, weather conditions. The city experiences four distinct seasons.
In July, the warmest month, high temperatures average 84 °F (29 °C) and low
temperatures 63 °F (17 °C). In January, the coldest month, high temperatures
average 29 °F (−2 °C) with low temperatures averaging 13 °F (−11 °C). According
to the National Weather Service, Chicago's highest official temperature reading
of 105 °F (40 °C) was recorded on July 24, 1934. The lowest temperature of
−27 °F (−32 °C) degrees was recorded on January 20, 1985.
Chicago's yearly precipitation averages about 38 inches (965 mm). Summer is
the rainiest season, with short-lived rainfall and thunderstorms more common
than prolonged rainy periods. Winter is the driest season, with most of the
precipitation falling as snow. Chicago's highest one day precipitation total was
6.49 inches (164 mm) which fell on August 14, 1987.