
33 Ill.2d 460 (1965)
211 N.E.2d 736
THE PEOPLE ex rel. William J. Scott et al., Petitioners,
v.
OTTO KERNER, Governor, et al., Respondents.
No. 39201.
Supreme Court of Illinois.
Opinion filed November 19, 1965.
KIRKLAND, ELLIS, HODSON, CHAFFETZ & MASTERS, of Chicago, (DON H. REUBEN, of counsel,) for petitioners.
WILLIAM G. CLARK, Attorney General, of Springfield, (RICHARD A. MICHAEL, Assistant Attorney General, of counsel,) for respondents.
Provisional congressional reapportionment adopted.
Mr. JUSTICE UNDERWOOD delivered the opinion of the court:
*461 In the earlier opinion in this cause (People ex rel. Scott v. Kerner, 32 Ill.2d 539), this court held that the Illinois congressional districts established by the General Assembly in 1961 (Ill. Rev. Stat. 1963, chap. 46, par. 156 f. 1) were invalid as violative of the equality of population principle set forth in Wesberry v. Sanders, 376 U.S. 1, 11 L.ed.2d 481, 84 S.Ct. 526. We expressed our confidence that the 74th General Assembly would, prior to adjournment, enact a constitutionally valid congressional reapportionment scheme, but nevertheless retained jurisdiction to insure that Illinois representatives in Congress would be elected in 1966 pursuant to a constitutionally valid plan. The legislature has since adjourned sine die without providing any congressional reapportionment plan.
On June 24, 1965, we ordered the parties to file suggestions concerning the manner in which Illinois congressional districts should be reapportioned in the event the General Assembly failed to act. Rather widely divergent proposals were filed. By our order of September 10, 1965, we indicated none of the suggestions so filed were completely acceptable, urged the parties to continue to attempt to reconcile their differences, and stated our intention, if no agreement was reached by October 1, to proceed to resolve the problem in conjunction with the United States District Court for the Northern District of Illinois, Eastern Division, which also had retained jurisdiction over the congressional reapportionment controversy. Kirby v. Illinois State Electoral Board, No. 65C75; Lusek v. Kerner, No. 65C81 (D. Ill. N.D.E.D.).
Subsequently, Chief Judge Campbell of that court acting under the pretrial provisions of Rule 16, Federal Rules of Civil Procedure, and with our knowledge and approval, conferred with counsel for the opposing parties in an attempt to compromise the controversy and reach agreement. On October 1, 1965, counsel informed Chief Judge Campbell and this court that complete agreement could not be *462 reached. Thereupon, based principally upon the areas of agreement by the parties, a judicially drafted plan was prepared as indicated in the pretrial memorandum of Chief Judge Campbell filed October 13 in that court and concurred in by Circuit Judge Latham Castle, presiding, and District Judge Bernard M. Decker, copies of which had theretofore been furnished members of this court. On October 13, 1965, this court and the Federal district court simultaneously announced approval of the provisional plan (a copy of which is attached as an appendix hereto, including legal descriptions, population data, and maps) and held that Illinois representatives in Congress shall be elected in 1966 from districts described therein.
We believe the provisional plan so adopted to be just, equitable and constitutionally valid. As stated in the Federal district court's pretrial memorandum, this plan utilizes "the nucleus of each existing congressional district, * * * enlarging or decreasing it to comply with the `one man, one vote' principle," thereby according the greatest possible effect to the 1961 legislatively devised apportionment plan which heretofore governed congressional representative elections. The district having the least population (No. 16-394, 481) deviates from the norm (420,048) by only 6.1%; the largest district (No. 8-451, 527) by 7.5%. Mathematical nicety is not required, and the principle of preservation of the integrity of historic political subdivisions more than justifies slight deviation from the hypothetical perfectly populated district. See Reynolds v. Sims, 377 U.S. 533, 579, 12 L.ed.2d 506, 84 S.Ct. 1362, 1391; People ex rel. Engle v. Kerner, 33 Ill.2d 11, 13.
We also believe it appropriate to here express our appreciation to counsel for the parties hereto and to Chief Judge Campbell, Circuit Judge Castle and District Judge Decker, whose initiative and cooperation have expedited the resolution of this troublesome apportionment problem in a manner we deem conducive to the best interests of the *463 people of this State and infinitely superior to the difficult situations prevailing in those jurisdictions wherein State and Federal courts have reached divergent conclusions on State apportionment matters.
Since apportionment problems are pre-eminently legislative responsibilities, the plan described in this opinion is required only by legislative nonfeasance and is therefore provisional in nature.
Provisional Congressional Reapportionment Adopted.

APPENDIX

POPULATION DATA FOR COOK COUNTY AREA CONGRESSIONAL DISTRICTS


                                    Deviation from
District Number    Population     Average of 420,048
      1             409,195             -2.6%
      2             425,454             +1.3%
      3             429,267             +2.2%
      4             415,838             -1.0%
      5             401,862             -4.3%
      6             420,109             +0.1%
      7             416,712             -0.8%
      8             451,527             +7.5%
      9             451,042             +7.4%
     10             433,935             +3.2%
     11             450,884             +7.3%
     13             407,052             -3.1%


LEGAL DESCRIPTIONS FOR COOK COUNTY AREA CONGRESSIONAL DISTRICTS
District 1: The Second Ward, the Third Ward, the Sixth Ward, the Twentieth Ward, that part of the Fourth Ward lying west of Cottage Grove Avenue, and that part of the Fourth Ward lying north of a line described as follows: Beginning at the center of the intersection of East 46th Street and South Cottage Grove Avenue, then eastward *464 on 46th Street to South Woodlawn Avenue, then south on Woodlawn to the junction with East 46th Street, then easterly on 46th Street to South Lake Park Avenue, then southerly on South Lake Park Avenue to East 47th Street, then easterly on 47th Street to Lake Michigan, that part of the Eighth Ward lying north of 99th Street and west of Stony Island Avenue, and that part of the Twenty-first Ward lying north of 99th Street and east of Stewart Avenue, all in the city of Chicago.
District 2: The Fifth Ward, the Seventh Ward, the Ninth Ward, the Tenth Ward, that part of the Fourth Ward lying east of Cottage Grove Avenue and south of a line described as follows: Beginning at the center of the intersection of East 46th Street and South Cottage Grove Avenue, then eastward on 46th Street to South Woodlawn Avenue, then south on Woodlawn to the junction with East 46th Street, then easterly on 46th Street to South Lake Park Avenue, then southerly on South Lake Park Avenue to East 47th Street, then easterly on 47th Street to Lake Michigan, and those parts of the Eighth Ward lying east of Stony Island Avenue and south of 99th Street, in the city of Chicago; the township of Calumet and that part of Thornton Township lying to the east and north of a line described as follows: Beginning at the northern boundary of Thornton Township and its intersection with Lincoln Avenue, southeast on Lincoln Avenue to Irving Avenue, south on Irving Avenue to Sibley Boulevard, east on Sibley Boulevard to the Calumet Expressway, south on the Calumet Expressway to its intersection with 159th Street, east on 159th Street to its intersection with the Little Calumet River, south and east along the river to its intersection with the eastern boundary of Thornton Township, in Cook County.
District 3: The Sixteenth Ward, the Seventeenth Ward, the Eighteenth Ward, the Nineteenth Ward, that part of the Thirteenth Ward lying south of 66th Street, and the *465 Twenty-first Ward except that part lying north of 99th Street and east of Stewart Avenue, in the city of Chicago; and that part of Worth Township lying within the village limits of Evergreen Park, in Cook County.
District 4: The townships of Bloom, Bremen, Lemont, Orland, Palos and Rich, that portion of Lyons Township lying west of a line described as follows: Beginning at the intersection of the northern boundary of Lyons Township and Eberly Avenue, south on Eberly Avenue to East Avenue, south on East Avenue as extended to its intersection with Louis Drive, southeast on Louis Drive to its intersection with Blackstone Avenue, southwest on Blackstone Avenue to its intersection with Beverly Lane, southeast on Beverly Lane to its intersection with Archer Avenue, southwest on Archer Avenue to its intersection with Elm Street as extended, south on Elm Street as extended to the southern boundary of Lyons Township, that portion of Thornton Township lying south and west of a line described as follows: Beginning at the northern boundary of Thornton Township and its intersection with Lincoln Avenue, southeast on Lincoln Avenue to Irving Avenue, south on Irving Avenue to Sibley Boulevard, east on Sibley Boulevard to the Calumet Expressway, south on the Calumet Expressway to its intersection with 159th Street, east on 159th Street to its intersection with the Little Calumet River, south and east along the river to its intersection with the eastern boundary of Thornton Township, and that part of Worth Township lying outside of the village limits of Evergreen Park, all in Cook County.
District 5: The Twelfth Ward, the Fourteenth Ward, the Fifteenth Ward, that part of the Eleventh Ward lying south of 31st Street, that part of the Thirteenth Ward lying norh of 66th Street, and that part of the Twenty-third Ward lying south of the Sanitary Drainage and Ship Canal, in the city of Chicago; the township of Stickney, and that part of Lyons township lying east of a line described as *466 follows: Beginning at the intersection of the northern boundary of Lyons Township and Eberly Avenue, south on Eberly Avenue to East Avenue, south on East Avenue as extended to its intersection with Louis Drive, southeast on Louis Drive to its intersection with Blackstone Avenue, southwest on Blackstone Avenue to its intersection with Beverly Lane, southeast on Beverly Lane to its intersection with Archer Avenue, southwest on Archer Avenue to its intersection with Elm Street as extended, south on Elm Street as extended to the southern boundary of Lyons Township.
District 6: The Twenty-fourth Ward, the Twenty-ninth Ward, the Thirtieth Ward, the Thirty-seventh Ward, that part of the Twenty-second Ward bounded by a line described as follows: Beginning at the intersection of Homan Avenue and Ogden Avenue, southwest on Ogden Avenue to its intersection with Drake Avenue, south on Drake Avenue to its intersection with Cermak Road, west on Cermak Road to its intersection with Central Park Avenue, south on Central Park Avenue as extended to its intersection with Pershing Road, west on Pershing Road to its intersection with Pulaski Road, north on Pulaski Road to its intersection with 19th Street, east on 19th Street to its intersection with Hamlin Avenue, north on Hamlin Avenue to its intersection with 18th Street, east on 18th Street to its intersection with Homan Avenue, south on Homan Avenue to the point of beginning at Ogden Avenue, and that part of the Twenty-third Ward lying north of the Sanitary Drainage and Ship Canal, in the city of Chicago; and the townships of Berwyn and Cicero, in Cook County.
District 7: The First Ward, the Twenty-fifth Ward, the Twenty-sixth Ward, the Twenty-seventh Ward, the Twenty-eighth Ward, that part of the Eleventh Ward lying north of 31st Street, and that part of the Twenty-second Ward bounded by a line described as follows: Beginning at *467 the intersection of Marshall Boulevard as extended and Ogden Avenue, southwest on Ogden Avenue to its intersection with Drake Avenue, south on Drake Avenue to its intersection with Cermak Road, west on Cermak Road to its intersection with Central Park Avenue, south on Central Park Avenue as extended to its intersection with Pershing Road, east on Pershing Road to its intersection with California Avenue, north on California Avenue to its intersection with 24th Boulevard, west on 24th Boulevard to its intersection with Marshall Boulevard, north on Marshall Boulevard as extended to the point of beginning at Ogden Avenue, all in the city of Chicago.
District 8: The Thirty-first Ward, the Thirty-second Ward, the Thirty-third Ward, the Thirty-fourth Ward, the Thirty-sixth Ward, the Thirty-fifth Ward, except that part lying north of Diversey Avenue and west of Pulaski Road, that part of the Thirty-ninth Ward lying south of Montrose Avenue and east of Tripp Avenue, that part of the Fortieth Ward lying south of the north branch of the Chicago River and east of Central Park Avenue and that part of the Forty-fourth Ward bounded by a line described as follows: Beginning at the intersection of the Chicago and North Western Railway right-of-way and Addison Street, east along Addison Street to its intersection with Southport Avenue, south along Southport Avenue to its intersection with Belmont Avenue, east along Belmont Avenue to its intersection with Racine Avenue, south along Racine Avenue to its intersection with Diversey Parkway, west along Diversey Parkway to its intersection with Southport Avenue, south along Southport Avenue to its intersection with Wrightwood Avenue, west along Wrightwood Avenue to its intersection with the Chicago and North Western Railway right-of-way, north along the Chicago and North Western Railway right-of-way to the point of beginning at Addison Street, all in the city of Chicago.
District 9: The Forty-second Ward, the Forty-third *468 Ward, the Forty-sixth Ward, the Forty-eighth Ward, the Forty-ninth Ward, the Forty-fourth Ward, except that part bounded by a line described as follows: Beginning at the intersection of the Chicago and North Western Railway right-of-way and Addison Street, east along Addison Street to its intersection with Southport Avenue, south along Southport Avenue to its intersection with Belmont Avenue, east along Belmont Avenue to its intersection with Racine Avenue, south along Racine Avenue to its intersection with Diversey Parkway, west along Diversey Parkway to its intersection with Southport Avenue, south along Southport Avenue to its intersection with Wrightwood Avenue, west along Wrightwood Avenue to its intersection with the Chicago and North Western Railway right-of-way, north along the Chicago and North Western Railway right-of-way to the point of beginning at Addison Street, and that part of the Fiftieth Ward north of Devon Avenue, all in the city of Chicago.
District 10: That part of the Thirty-eight Ward in the city of Chicago lying to the west of the Des Plaines River in Cook County and in Du Page County; the townships of Maine, Oak Park, Proviso, River Forest and Riverside, that part of Leyden township lying to the west of a line described as follows: Beginning at the southern boundary of Leyden Township and its intersection with Harlem Avenue, north on Harlem Avenue to Wellington Avenue, west on Wellington Avenue to Oriole Avenue, north on Oriole Avenue to Belmont Avenue, west on Belmont Avenue to its intersection with the Des Plaines River, north along the river to its intersection with Higgins Road, southeast on Higgins Road to Cumberland Avenue, north on Cumberland Avenue to its intersection with the southern boundary of Maine Township, and that part of Norwood Park Township lying to the north of Higgins Road, in Cook County.
District 11: The Forty-first Ward, the Forty-fifth Ward, the Forty-seventh Ward, that part of the Thirty-fifth *469 Ward lying north of Diversey Avenue and west of Pulaski Road, that part of the Thirty-eighth Ward lying east of the Des Plaines River, the Thirty-ninth Ward except that part lying south of Montrose Avenue and east of Tripp Avenue, the Fortieth Ward except that part lying south of the north branch of the Chicago River and east of Central Park Avenue, and that part of the Fiftieth Ward lying south of Devon Avenue, in the city of Chicago; that part of Leyden Township lying to the east of a line described as follows: Beginning at the intersection of Harlem Avenue and North Avenue, north on Harlem Avenue to its intersection with Wellington Avenue, west on Wellington Avenue to its intersection with Oriole Avenue, north on Oriole Avenue to its intersection with Belmont Avenue, west on Belmont Avenue to its intersection with the Des Plaines River, north along the Des Paines River to its intersection with Higgins Road, southeast on Higgins Road to its intersection with Cumberland Avenue, north on Cumberland Avenue to its intersection with Devon Avenue, being the southern boundary of Maine Township, and that part of Norwood Park Township lying south of Higgins Road, in Cook County.
District 13: The city of Evanston, the townships of Elk Grove, New Trier, Niles, Northfield, Palatine, Schaumberg, and Wheeling, all in Cook County.
*470 


*471 POPULATION DATA FOR DOWNSTATE CONGRESSIONAL DISTRICTS


                                   Deviation from
District Number   Population    Average of 420,048
     12            394,714            -6.0%
     14            439,182            +4.6%
     15            410,650            -2.2%
     16            394,481            -6.1%
     17            428,519            +2.0%
     18            401,503            -4.4%
     19            410,402            -2.3%
     20            401,919            -4.3%
     21            417,760            -0.5%
     22            441,332            +5.4%
     23            412,709            -1.9%
     24            415,110            -0.9%


LEGAL DESCRIPTIONS FOR DOWNSTATE CONGRESSIONAL DISTRICTS
District 12: The counties of Lake and McHenry, and the townships of Barrington and Hanover in Cook County.
District 14: All of Du Page County except for that part that lies within the boundaries of O'Hare Field in the city of Chicago, and the townships of Du Page, Joliet and Lockport in Will County.
District 15: The counties of DeKalb, Grundy, Kane, Kendall, and La Salle.
District 16: The counties of Boone, Carroll, Jo Daviess, Lee, Ogle, Stephenson, and Winnebago.
Distict 17: The counties of Ford, Iroquois, Kankakee, Livingston, McLean, and Vermilion, and all of Will County except for the townships of Du Page, Joliet and Lockport.
District 18: The counties of Bureau, Marshall, Mason, Menard, Peoria, Putnam, Stark, Tazewell, and Woodford.
District 19: The counties of Fulton, Henderson, Henry, Knox, Mercer, Rock Island, Warren, and Whiteside.
*472 District 20: The counties of Adams, Brown, Calhoun, Cass, Greene, Hancock, Jersey, Morgan, McDonough, Pike, Sangamon, Schuyler and Scott.
District 21: The counties of Alexander, Edwards, Franklin, Gallatin, Hamilton, Hardin, Jackson, Jefferson, Johnson, Massac, Monroe, Perry, Pope, Pulaski, Randolph, Saline, Union, Wabash, Washington, Wayne, White and Williamson.
District 22: The counties of Champaign, Clark, Coles, Cumberland, De Witt, Douglas, Edgar, Logan, Macon, Moultrie, and Piatt.
District 23: The counties of Bond, Christian, Clay, Clinton, Crawford, Effingham, Fayette, Jasper, Lawrence, Macoupin, Marion, Montgomery, Richland, and Shelby, and the following townships in Madison County: Helvetia, Saline, Leef, New Douglas, Marine, Alhambra, Olive, Hamel, Omphghent, Moro, Foster, Alton, and Godfrey.
District 24: St. Clair County and all of Madison County except for the townships of Helvetia, Saline, Leef, New Douglas, Marine, Alhambra, Olive, Hamel, Omphghent, Moro, Foster, Alton, and Godfrey.
*473 
