See main article: 1848 United States presidential election.
| Election Name: | 1848 United States presidential election in Illinois |
| Country: | Illinois |
| Flag Year: | 1818 |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1844 United States presidential election in Illinois |
| Previous Year: | 1844 |
| Next Election: | 1852 United States presidential election in Illinois |
| Next Year: | 1852 |
| Election Date: | November 7, 1848 |
| Image1: | Lewis Cass circa 1855.jpg |
| Nominee1: | Lewis Cass |
| Party1: | Democratic Party (United States) |
| Home State1: | Michigan |
| Running Mate1: | William O. Butler |
| Electoral Vote1: | 9 |
| Popular Vote1: | 55,952 |
| Percentage1: | 44.91% |
| Nominee2: | Zachary Taylor |
| Party2: | Whig Party (United States) |
| Home State2: | Louisiana |
| Running Mate2: | Millard Fillmore |
| Electoral Vote2: | 0 |
| Popular Vote2: | 52,853 |
| Percentage2: | 42.42% |
| Image3: | Portrait of Martin Van Buren (cropped).jpg |
| Nominee3: | Martin Van Buren |
| Party3: | Free Soil Party |
| Home State3: | New York |
| Running Mate3: | Charles F. Adams |
| Electoral Vote3: | 0 |
| Popular Vote3: | 15,702 |
| Percentage3: | 12.60% |
| Map Size: | 200px |
| President | |
| Before Election: | James K. Polk |
| Before Party: | Democratic Party (United States) |
| After Election: | Zachary Taylor |
| After Party: | Whig Party (United States) |
The 1848 United States presidential election in Illinois took place on November 7, 1848, as part of the 1848 United States presidential election. Voters chose nine representatives, or electors to the Electoral College, who voted for President and Vice President.
Illinois narrowly voted for the Democratic candidate, Lewis Cass, over Whig candidate Zachary Taylor and Free Soil candidate Martin Van Buren. Cass won Illinois by a tight margin of 2.49%. This was the last time until 2000 that Illinois would back a losing Democrat in a presidential election and the last time until 2004 that they would back a Democrat that lost the popular vote.