Here is a little bit of history behind this commemorative:
100,058 pieces coined during August 1918 at the Philadelphia Mint with 58 pieces reserved for annual assay, none melted. The obverse was designed and modeled by George T. Morgan, the reverse by
John R. Sinnock. Distributed by The Illinois Centennial Commission, Hugh S. Magill, Jr., Director of the Centennial Celebration.
Approved by Congress on June 1, 1918 and issued to commemorate the one hundredth anniversary of the admission of the State of Illinois into the Union.
Design:Obverse: Bust of Lincoln without beard (pre-1860) facing right; around edge, in Roman letters: CENTENNIAL

OF

THE

STATE

OF

ILLINOIS Below bust, 1918 In field, behind head, in small Gothic letters: IN GOD WE TRUST In front: LIBERTY. The Lincoln portrait is copied from a statue by Andrew O'Connor which was unveiled at Springfield, Illinois in August 1918.
Reverse: Eagle to left, with upraised wings, standing with left foot on rock and right on the United States shield; in beak of eagle a ribbon with motto incused in small Gothic letters, reading vertically: STATE / SOVEREIGNTY / NATIONAL / UNION In left field, rising sun, above in small Gothic letters: E / PLURIBUS / UNUM Around top border:

UNITED

STATES

OF

AMERICA

At bottom: HALF DOLLAR .
"At the request of the Illinois Centennial Commission, Congressman Loren E. Wheeler of the Twenty-first Illinois Congressional District introduced a bill in Congress providing for the coinage of a special coin in commemoration of the Centennial of the admission of Illinois into the Union. After the passage of the bill by Congress authorizing the coinage of one hundred thousand half dollars, every effort was made to expedite the distribution of the coins among the people of the State as souvenirs of the Centennial year.
One hundred thousand fifty cents pieces with a special design commemorative of the Illinois Centennial were issued. The design was determined upon by the Director of the Mint and the Secretary of the Treasury, but was suggested by the Centennial Commission. As a result of a conference with the Superintendent and Chief Engraver of the United States Mint, it was agreed that the coin should have the head of Lincoln on the obverse side and the seal of Illinois on the reverse side, with the inscription 'Centennial of the State of Illinois, 1818-1918.' The Chief Engraver of the Mint prepared the models from which the dies were made.
The coins were distributed during the Centennial year to county or centennial associations at par value. These associations disposed of the fifty cent pieces for one dollar each, the proceeds of the sale being used for local Celebrations or some phase of war relief work.
The coin has been much admired by numismatists and it has been purchased by them and distributed throughout the entire United States.
"11 The Centennial of the State of Illinois; Report of the Centennial Commission. Compiled by Jesse Palmer Weber, Secretary of the Commission, 1920.