| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| 2024 | D | 1,447,821 | 583,852 | 2,079,239 | |
| 2020 | D | 1,725,973 | 558,269 | 2,325,405 | |
| 2016 | D | 1,611,946 | 453,287 | 2,180,344 | |
| 2012 | D | 1,488,537 | 495,542 | 2,014,819 | |
| 2008 | D | 1,629,024 | 487,736 | 2,137,466 | |
| 2004 | D | 1,439,724 | 597,405 | 2,049,434 | |
| 2000 | D | 1,280,547 | 534,542 | 1,865,907 | |
| 1996 | D | 1,153,289 | 461,557 | 1,726,666 | |
| 1992 | D | 1,249,533 | 605,300 | 2,146,655 | |
| 1988 | D | 1,129,973 | 878,582 | 2,026,144 | |
| 1984 | D | 1,112,641 | 1,055,558 | 2,180,735 | |
| 1980 | D | 1,124,584 | 856,574 | 2,163,097 | |
| 1976 | D | 1,180,814 | 987,498 | 2,209,748 | |
| 1972 | R | 1,063,268 | 1,234,307 | 2,311,037 | |
| 1968 | D | 1,181,316 | 960,493 | 2,336,538 | |
| 1964 | D | 1,537,181 | 895,718 | 2,432,899 | |
| 1960 | D | 1,378,343 | 1,059,607 | 2,445,269 | |
| 1956 | R | 977,821 | 1,293,223 | 2,276,844 | |
| 1952 | R | 1,172,454 | 1,188,973 | 2,367,939 | |
| 1948 | D | 1,216,636 | 1,015,800 | 2,245,899 | |
| 1944 | D | 1,275,367 | 924,659 | 2,206,191 | |
| 1940 | D | 1,168,141 | 938,454 | 2,114,807 | |
| 1936 | D | 1,253,164 | 701,206 | 2,009,457 | |
| 1932 | D | 919,231 | 690,146 | 1,664,232 | |
| 1928 | R | 716,283 | 812,063 | 1,540,171 | |
| 1924 | R | 226,141 | 688,973 | 1,113,652 | |
| 1920 | R | 197,499 | 635,197 | 893,137 | |
| 1916 | R | 379,438 | 435,695 | 849,913 | |
| 1912 | D | 130,702 | 74,851 | 429,312 | |
| 1908 | R | 152,990 | 230,400 | 415,091 | |
| 1904 | R | 103,762 | 229,848 | 392,945 | |
| 1900 | R | 186,193 | 203,760 | 401,134 | |
| 1896 | R | 152,146 | 221,823 | 379,608 | |
| 1892 | D | 144,604 | 111,254 | 261,330 | |
| 1888 | — | — | — | — | |
| 1884 | — | — | — | — | |
| 1880 | — | — | — | — | |
| 1876 | — | — | — | — |
Cook County's presidential margins have exceeded D+40 in recent cycles, driven by Chicago's dense, majority-minority electorate. Its 5.3 million residents make it the second-most populous county in the United States.
The Democratic margin in Cook County has been steady. It reached its modern peak at fifty-three points in 2008; the 2024 margin was forty-two points, still in line with the county's long pattern.
Cook County's political identity is inseparable from its demographic profile: a 44% non-Hispanic-white share, a median household income of $83,498, and the full diversity of a major metropolitan center. The county's voting pattern resembles other major urban centers most closely — Allendale County and Essex County.
