Illinois constitution
Article VI
Section 19

A State's Attorney shall be elected in each county in
1972 and every fourth year thereafter for a four year term.
One State's Attorney may be elected to serve two or more
counties if the governing boards of such counties so provide
and a majority of the electors of each county voting on the
issue approve. A person shall not be eligible for the office
of State's Attorney unless he is a United States citizen and
a licensed attorney-at-law of this State. His salary shall be
provided by law.