Illinois 203 (disambiguation)

Illinois 203 could refer to:

• Illinois Route 203, a state highway, formerly part of Illinois Route 3 and U.S. Route 66, near St. Louis

School districts

• Elwood Community Consolidated School District 203 in Will County
• Naperville Community Unit School District 203 in DuPage County
• New Trier Township High School District 203 in Cook County
• O'Fallon Township High School District 203 in St. Clair County
• Orangeville Community Unit School District 203 in Stephenson County
• Vandalia Community Unit School District 203 in Fayette County
• Westmer Community Unit School District 203 in Mercer County