Question: What Congressional District did John Shimkus represent before the 20th Congressional District of Illinois?

Context:
Illinois's 19th congressional district
The 19th Congressional District of Illinois was a congressional district in Illinois.
 The district became obsolete for 2013's 113th Congress, as population growth in Illinois was slower compared to other states.
 It was last represented by Republican John Shimkus, who was redistricted to the 15th district.
Illinois's 20th congressional district
The 20th Congressional District of Illinois was a congressional district for the United States House of Representatives in Illinois.
 It was eliminated as a result of the 2000 Census.
 It was last represented by John Shimkus who was redistricted into the 19th District.
Illinois's 15th congressional district
The 15th Congressional District of Illinois is located in eastern/southeastern Illinois.
 Republican John Shimkus represents the district.
Adam Kinzinger
Adam Daniel Kinzinger (born February 27, 1978) is the U.S. Representative for Illinois 's 16 congressional district .
 He is a member of the Republican Party.
 He was first elected to Congress in 2010, winning election to represent Illinois's 11th congressional district.
 After redistricting, he was re-elected to Congress in 2012, 2014, and 2016 to represent Illinois's 16th congressional district.
Colorado's 4th congressional district
Colorado's 4th congressional district is a congressional district in the U.S. state of Colorado.
 Located in the eastern part of the state, the district encompasses most of the rural Eastern Plains as well as the larger city of Greeley, Lamar, and Castle Rock along Colorado's Front Range in eastern Colorado.
 Interactive map of Colorado's 4th Congressional District.
Wisconsin's 7th congressional district
Wisconsin's 7th congressional district is a congressional district of the United States House of Representatives in northwestern and central Wisconsin; it is the largest congressional district in the state geographically, covering 20 counties (in whole or part), for a total of 18,787 sq mi.
 The district contains the following counties: Ashland, Barron, Bayfield, Burnett, Chippewa, Clark (partial), Douglas, Iron, Langlade (partial), Lincoln, Marathon, Oneida, Polk, Portage, Price, Rusk, Sawyer, Taylor, Washburn and Wood.
Massachusetts's 5th congressional district
Massachusetts' 5th congressional district is a congressional district in eastern Massachusetts.
 The district is represented by Katherine Clark.
 Massachusetts congressional redistricting after the 2010 census has changed the borders of the district starting with the elections of 2012, with the new 3rd district largely taking the place of the old 5th.
 The 5th district had covered many of the communities represented in the old 7th district.
 As of 2010, the population of the 5th congressional district was 727,515.
 On July 15, 2013, Ed Markey resigned from the seat to become the junior Senator from Massachusetts.
 On December 10, 2013, Democrat Katherine Clark won a special election to fill the seat for the remainder of the 113th Congress.
 She was sworn into office on December 12, 2013.
Frederick R. Lehlbach
Frederick Reimold Lehlbach (January 31, 1876 – August 4, 1937) was an American lawyer and politician.
 As a Republican, Lehlbach served as the U.S. Representative for New Jersey's 10th congressional district from 1915 to 1933 and as the representative from New Jersey's 12th congressional district from 1933 to 1937.
 Lehlbach was also the nephew of Herman Lehlbach, a former U.S. Representative from New Jersey's 6th congressional district who served from 1885 to 1891.
John Shimkus
John Mondy Shimkus ( , born February 21, 1958) is the U.S. Representative for Illinois 's 15 congressional district , since 1997.
 He is a member of the Republican Party.
Barbara Lee
Barbara Jean Lee (born July 16, 1946) is the U.S. Representative for California 's 13th congressional district , serving East Bay voters from 1998 to 2013 during a time when the region was designated California 's 9 congressional district .
 She is a member of the Democratic Party.
 She was the first woman to represent the 9th district and is also the first woman to represent the 13th district.
 Lee was the Chair of the Congressional Black Caucus and was the Co-Chair of the Congressional Progressive Caucus.
 Lee is notable as the only member of either house of Congress to vote against the authorization of use of force following the September 11, 2001 attacks.
 This made her a hero among many in the anti-war movement.
 Lee has been a vocal critic of the war in Iraq and supports legislation creating a Department of Peace.

Answer: Illinois 's 15 congressional district