The Chicago River
is 156 miles (251 km) long, and flows through downtown Chicago
. Though not especially long, the river is notable for the 19th century civil engineering
feats that directed its flow south, away from Lake Michigan
, into which it previously emptied, and towards the Mississippi River
basin. This was done for reasons of sanitation. The river is also noted for the local custom of dyeing it green on St. Patrick's Day
Originally, the river flowed into Lake Michigan. Its course jogged southward from the present river to avoid a baymouth bar
, entering the lake at about the level of present day Madison Street
. Today, the Main Stem of the Chicago River flows due west from Lake Michigan, past the Wrigley Building
and the Merchandise Mart
to Kinzie Street, where it meets the North Branch of the river. The North Branch is formed by the West Fork, the East Fork (also known as the Skokie River
) and the Middle Fork, which join into the North Branch at Morton Grove, Illinois
. From downtown, the river flows south along the South Branch, and into the Illinois and Michigan Canal
and Chicago Sanitary and Ship Canal
. From there the water flows into the Des Plaines River
and eventually reaches the Gulf of Mexico
The first non-Native American
to settle near the Chicago River was Jean Baptiste Pointe du Sable
, who built his farm on the northern bank at the mouth of the river in the 1780s In 1808 Fort Dearborn
was constructed on the opposite bank on the site of the present-day Michigan Avenue Bridge
. In the 1830s and 1840s considerable effort was made to cut a channel through the sandbar to improve shipping. In 1900 the river's flow was reversed in order to keep Lake Michigan clean. In 1915, the Eastland,
an excursion boat docked at the Clark Street bridge, rolled over, killing 812 passengers. In 1928, the South Branch of the Chicago River between Polk and 18th Street was straightened and moved ¼ miles (400 m) west to make room for a railroad terminal.
Reversing the flow
Originally, the river flowed into Lake Michigan. As Chicago grew this allowed sewage and other pollution into the clean-water source for the city. This contributed to several public health
issues including some problems with typhoid
. Starting in the 1850s much of the flow was diverted across the Chicago Portage
into the Illinois and Michigan Canal. In 1900, the Sanitary District of Chicago
, then headed by Rudolph Hering
, completely reversed the flow of the river using a series of canal locks
and caused the river to flow into the newly completed Chicago Sanitary and Ship Canal (see Ask Chicagoist: River Reversal?
). Before this time the Chicago River was known by many local residents of Chicago as "the stinking river" because of the massive amounts of sewage
which poured into the river from Chicago's booming industrial economy. Through the 1980s, the river was quite dirty and often filled with garbage
; however, during the 1990s, it underwent extensive cleaning as part of an effort at beautification by Chicago Mayor Richard M. Daley
Recently, researchers at the University of Illinois at Urbana-Champaign created a three-dimensional, hydrodynamic simulation of the Chicago River, which suggested that density currents are the cause of an observed bi-directional wintertime flow in the river. At the surface, the river flows east to west, away from Lake Michigan, as expected. But deep below, near the riverbed, water travels west to east, toward the lake.
All outflows from the Great Lakes Basin are regulated by the joint U.S.-Canadian Great Lakes Commission and the outflow through the Chicago River is set under a U.S. Supreme Court decision (1967, modified 1980 and 1997). The city of Chicago is allowed to remove 3200 cubic feet per second (91 m³/s) of water from the Great Lakes system; about half of this, 1 billion US gallons a day (44 m³/s), is sent down the Chicago River, while the rest is used for drinking water. In late 2005 the Alliance for the Great Lakes proposed separating the Great Lakes and Mississippi River basins.
On April 13, 1992 the Chicago Flood
occurred when a pile driven into the riverbed caused stress fractures in the wall of a long-abandoned tunnel of the Chicago Tunnel Company
near Kinzie Street. Most of the 60-mile (97 km) network of underground freight railway, which encompasses much of downtown, was eventually flooded along with the lower levels of buildings it once serviced and attached underground shops and pedestrian ways.
The Chicago River has been highly affected by the industrial and residential areas around with attendant changes to the quality of the water and riverbanks. Several species of warmwater fish are known to inhabit the river including largemouth
and smallmouth bass
, rock bass
. The river also has a large population of crayfish
. The South Fork of the Main (South) Branch, which was the primary sewer for the Union Stock Yards
and the meatpacking
industry, was once so polluted that it became known as Bubbly Creek
. Illinois has issued advisories regarding eating fish from the river due to PCB
contamination, including a "do not eat" advisory for carp more than 12 inches long. There are concerns that silver carp
and bighead carp
, now invasive species
in the Mississippi and Illinois Rivers
, may reach the Great Lakes
through the Chicago River.
St. Patrick's Day
Every year on St. Patrick's Day
, the river is dyed greener than it normally is.
Bill King, the administrator of Chicago's St. Patrick's Day committee, stated that "the idea of dyeing the Chicago River green originally came about by accident when a group of plumbers were using fluorescein dye to trace illegal substances that were polluting the river".
The United States Environmental Protection Agency (EPA) outlawed the use of fluorescein for this purpose, since it was proven to be harmful to the river. The secret ingredients used to dye the river green today are claimed to be safe and not harmful to the thousands of living organisms that find a habitat in the Chicago river.
The first bridge across the Chicago River was constructed over the north branch near the present day Kinzie Street in 1832. A second bridge, over the south branch near Randolph Street, was added in 1833. The first movable bridge was constructed across the main stem at Dearborn Street in 1834. Today, the Chicago River has 38 movable bridges spanning it, down from a peak of 52 bridges. These bridges are of several different types, including trunnion bascule, scherzer rolling lift, swing bridges and vertical lift bridges.
The following bascule bridges cross the river (and its south branch) into the Chicago Loop:
Many of Chicago's landmark buildings line the banks of the river. A partial list follows: