State broadhead legality
Broadhead legality varies by state on four points: (1) whether mechanical broadheads are legal at all, (2) minimum cut diameter, (3) minimum blade count, (4) whether cut-on-contact is required. Miss any of these and a legal hunt turns into a citation. This page is a research summary. Not legal advice. Confirm with your state fish and wildlife agency before your season.
Mechanical broadhead legality
Mechanical broadheads are legal in the majority of US states for big game (whitetail, mule deer, elk, black bear). States that ban or restrict mechanical broadheads for big game at time of writing include Idaho and Oregon (both check current season regs). Some states restrict mechanicals to specific seasons (archery only, no muzzleloader).
Minimum cut diameter
The most common minimum is 7/8 in cut diameter (0.875 in). This applies broadly across Western states. Notably: Oregon requires 1 in minimum cut for elk. Colorado (see Colorado) requires 7/8 in for big game. Kansas and Illinois have no cut diameter minimum but require broadheads for big game.
State pages
Per-state pages: Colorado, Pennsylvania, Wisconsin, Idaho, Oregon, more added by season.
Related reading
See the fixed-blade guide, mechanical guide, and the broadheads pillar.