Upon the organization of the Northwest Territory, Gen. Arthur St. Clair was appointed Governor. In the spring of 1790, in company with the Territorial Judges, he went to Cahokia, where, by proclamation, he organized the county of St. Clair, the first individual county formed in what is now the State of Illinois, and its seat of justice was fixed at Kaskakin. Randolph was the next county created in Illinois, and the date of its organization extends back to 1795. These were the only counties formed until after the dawning of the nineteenth century. At the session of the Territorial Legislature of 1811-12, Madison, Galatin and Johnson were organized, and Edwards at the session of 1814. The session of 1816, White, Jackson, Monroe, Pope and Crawford were organized and at the last session of the Territorial Legislature Franklin, Washington, Union Bond and Wayne came into existence. At the first ssesion of the Legislature after Illinois was admitted into the Union as a State, Jefferson County was formed, under the following act entitled an act for forming a separate county of of Edwards and White Counties, approved March 26, 1819.

Be it enacted by the people of the State of Illinois represented in the General Assembly. That all that tract of country within the following boundaries to wit: Beginning where the line between Ranges 4 and 5 east intersects the base line; thence west with said line to the Third Principal Meridian thence south twenty-four miles: thence east twenty-four miles thence north to the place of beginning, shall constitute a separate county, to be called "Jefferson", and for the purpose of fixing the permanent seat of justice therein the following persons are appointed Commissioners: Ambrose Maulding, Lewis Barker, Robert Shipley, James A. Richardson and Richard Graham, which said Commissioners, or a majority of them, being duly sworn before some Judge or Justice of the Peace in this State to faithfully take into view the convenience of the people, the situation of the settlement, with an eye to future population, and the eligibility of the place, shall meet on the 2d Monday of May, at the house of William Casey, in said county, and proceed to examine and determine on the place for the permanent seat of justice and designate the same; provided: The proprietor or proprietors of the land shall give to the county for the purpose of erecting public buildings, a quantity of land, not less than twenty acres, to be laid out in lots and sold for that purpose; but should the proprietor or proprietors refused or neglect to make the donation aforesaid, then and in that case it shall be the duty of said Commissioners to fix on some other place for the seat of justice as convenient as may be to the inhabitants of said county, which place fixed and determine upon, the said Commissions shall certify under their hands and seals and return the same to the next Commissioners' Court in the county aforesaid, which court shall cause an entry thereof to be made in their book of record, and until the public buildings be erected, the courts shall be held at the house of William Casey, in the said county.

SEC. 2. Be it further enacted, That the Commissioners aforesaid shall receive a compensation of two dollars for each and every day they may be necessarily employed in fixing the the aforesaid seat of justice, to be paid out of the county treasurey by an order from the Commissioner's Court.

SEC. 3. Be it further enacted, That the citizens of Jefferson County are hereby declared entitled, in all respects, to the same rights and privileges as are allowed in general with the other counties in this State.

SEC. 4. Be it further enacted, That the county of Jefferson shall vote in conjunction with White County for Representatives to the General Assembly of the State, and it shall be the duty of the Clerks of said counties to meet at the court house in White County, within ten days after such elections, and make a certificate, signed by both Clerks, to the persons duly elected; and if the said Clerks shall fail to do the same they shall forfeit and pay the sum of one hundred dollars, for the use of said counties, to be recovered by action of debt in the county in which such delinquent Clerk may reside.

SEC. 5. Be it further enacted, That the county of Jefferson shall be and compose a part of the Second Judicial Circuit, and the courts shall be holden therein at such times as shall be specified by law.

This was followed by a supplemental act, entitled "An act supplemental to an act for laying off anew county out of the counties or Edwards and White", approved March 29, 1819, as is as follows:

Be it enacted by the people of the State of Illinois, represented in the General Assembly. That all that tract or part of country lying north of the county of Jefferson and west of the county of Wayne, and not included within the limits of the said counties of Jefferson and Wayne, established by the act to which this is a supplement, be and the same is hereby attached to and form a part of the said county of Jefferson, and that the inhabitants there of have and enjoy all the rights and privileges, as far as may be, that the inhabitants of the county of Jefferson have and enjoy.

SEC. 2. Be it further enact, That the county of Jefferson be and the same is hereby attached to the Fourth Judicial Circuit of the State, etc. etc.

Source:
History of Jefferson County, Illinois
Edited by William Henry Perrin
Chicago:
Globe Publishing Co. Historical Publishers,
183 Lake Street,
1883