What Collision Data Tell Us About Deer Hunting Near Cities

Across six counties near Chicago, deer-vehicle collisions for each billion vehicle miles declined 25% to 57% when comparing 2020 to 2024 with 1989 to 1993. Illinois' median county finished 4% above its earlier rate. The data establish that difference without explaining whether hunting produced it. Ten counties elsewhere belonged to the 15 strongest declines across Illinois' 102 counties, and anything affecting collision totals or driving mileage can change the rate. Here, we examine the conclusions these records support and their limits, then draw five questions for towns from three published local programs.

The Illinois Department of Natural Resources (IDNR) measures collisions using accidents exceeding $1,500 in damage for every billion miles traveled within a county. That rate is the sole crash measure used here. Collision totals rise and fall with traffic, explaining why crash maps mislead when presented as evidence about deer. A town provides little useful information by citing a crash total without driving mileage.

The county dataset contains 3,672 rows: one record for every county each year, covering 102 counties through 36 years from 1989 to 2024. Every county carries a 0.0 value for 1996 in the source. Treating those values as missing leaves 3,570 usable county-years. The five-year averages put Cook at 23.1 initially and 17.4 later, DuPage at 28.0 and 15.3, Lake at 110.6 and 54.1, Kane at 151.6 and 76.9, Will at 125.3 and 54.9, and McHenry at 308.5 and 132.5. For Illinois' median county, the corresponding rates were 305.6 and 318.8. Its peak of 513.9 occurred in 2006, reaching 1.68 times the initial level.

The plotted trends began diverging during the late 1990s. For both series, we set the mean for 1989 to 1993 at 100. Using the averages for 1999 to 2003, the middle index among the six collar counties reached 74.4; the median county's index reached 144.2. In 2024, those respective indexes were 53.3 and 97.2.

A declining rate in these records cannot identify hunting as its cause. Across 102 counties, 40 had lower rates when comparing 2020 to 2024 with 1989 to 1993; 62 had higher rates. Ranked by the size of their declines, the six counties placed 2 and 3, followed by 8 and 12, then 13 and 23. That makes the collar counties unusual, although others share the pattern. Pulaski County leads with a 59% decline. Winnebago holds fourth place, Greene fifth, and Ogle sixth. Another six counties beyond the collar also appear among the 15 strongest declines.

The table cannot explain those counties' declines. With no histories of hunts or culls, it provides no way to determine how the rates would have changed without deer management. When a town presents its decline as proof, it documents a change without establishing the reason.

Compared with other Illinois counties, hunter-reported take is small in this group. During 2024, Cook hunters reported 128 deer, all taken with bows, over a land area of 945 square miles. DuPage hunters reported 39. Will and McHenry are the two counties with substantial firearm harvests; bows accounted for 71% and 73% of their respective reported totals. During 2020 to 2024, yearly reported take for each square mile averaged 0.12 to 1.68 across the six counties. Illinois' median county averaged 2.75. The archery map identifies where bows account for the greatest share.

Cook provides the clearest example. According to the Forest Preserves of Cook County, firearm hunting is prohibited within Cook County, and bowhunting has worked in only a narrow set of situations. Its deer management employs professional sharpshooters after dusk with permits issued by IDNR. Whether those culls appear in the hunter-reported totals is unspecified in the harvest table. These records therefore cannot assign Cook's 25% decline to hunters.

For the 100 counties whose harvest records cover all of 2020 to 2024, higher reported take relative to land area generally accompanied a greater collision-rate decline. We calculated that decline using average rates for 2005 to 2009 and for 2020 to 2024. The association is weak: its rank correlation equals -0.24, with p = 0.017. IDNR describes increasing hunting permit allocations when county collision rates climb. Under that rule, a high-rate county receives additional permits, making permit allocations a response to the rate. This is one reason the relationship cannot establish that hunting reduced it. In 2024, all six counties recorded rates below their IDNR targets, and 74 counties out of 102 met or bettered their targets.

Three published examples explain the value of these questions. Fox Chapel, Pennsylvania, recorded 2,980 deer removals during 15 years, with archery accounting for 68%. The study describes declining bowhunter participation and bow harvest during the effort. Beginning in 2003, police sharpshooters removed more deer than bowhunters. Pittsburgh explains on its deer management page that archery has prevented herd growth, but cannot shrink the herd on its own. Its bowhunters harvested 199 deer during 2024-25, followed by 142 during 2025-26. Fairfax County, Virginia, reported a fiscal 2024 removal total of 773 deer: archery accounted for 703 and sharpshooting for 70. After chronic wasting disease was detected there, the county stopped allowing bait during camera surveys.

Begin by examining the population estimate. Mississippi State's study using tagged deer examined fenced areas measuring 630 and 2,000 acres. About 90% of deer were photographed using one camera for every 100 acres during 14 days. Coverage dropped to roughly 68% during winter and 55% during fall with one camera for every 200 acres. To evaluate a count from a camera survey, request the number of cameras per unit area and how long the survey lasted. The estimate is difficult to evaluate without that information.

Collision rates reflect both crash totals and driving mileage. Our table contains the resulting rate alone, preventing us from separating fewer collisions from increased traffic as explanations for a decline. Over 36 years, housing, traffic, hunting, culling, roads and land use could all have changed. None appears in the table. Each year's median represents the middle of the 102 county rates rather than a statewide rate weighted by traffic.

Under Public Act 95-754, the property damage triggering a mandatory crash report increased from $500 to $1,500 effective 1 January 2009. The threshold remains $500 when an involved vehicle is uninsured but subject to Illinois' liability-insurance requirement. We were unable to establish whether IDNR recalculated the earlier data. The records contain no clear break at the change's effective date. Illinois' median county recorded a -0.2% rate change between 2008 and 2009. Declines across four collar counties ranged from 8.0% to 19.7%; increases were 3.5% in DuPage and 9.2% in McHenry.

Harvest records begin with 2005 and measure deer reported by hunters rather than herd size. For goals, we used our saved version of IDNR's county targets for 2023 without retrieving a fresh copy for this article. The association between harvest and collision rates establishes no causal direction.

We think deer programs should be evaluated by their collision rates across multiple years. Residents and hunters should therefore request five written answers: the deer-counting method, removals broken out by method, the collision rate relative to driving mileage, hunter participation, and whether the program aims to keep herd size steady or reduce it. With all five answers, residents can evaluate a town using its own figures. Even complete answers document the work without establishing its effects. When a town cannot provide some answers, its program lacks measurement but is not a failure. A fair response is to request publication of the missing figures ahead of the next season. Every Illinois county and year appears in the county series.