A speed trap is a location whose police have a reputation for writing an unusually high number of traffic tickets, usually for speeding. Sometimes, the posted speed limits are not easily seen; in other places, police have chosen to strictly enforce speed limits, and the limits are typically set far lower than warranted by road conditions or population. Speed traps often are found in small towns, often near major highways, in which travelers are unlikely to return to challenge a speeding ticket.

Some communities with reputations as speed traps have a disproportionately large number of their local workforce involved in law enforcement or judiciary occupations.

In some small towns and counties, traffic fines make up a large fraction of the income of the local government, which gives the police an incentive to write tickets. In the state of Texas, this conflict of interest was so severe that the state legislature passed a law limiting the fraction of revenue that a local government could derive from traffic tickets. Several other states have passed similar laws.

Another tactic used by some states to limit this conflict of interest is to require that a substantial amount of all local traffic ticket revenue go directly into the state treasury, instead of having all revenue go to the issuing jurisdiction.

In the village of New Rome, Ohio, a speed trap that has received national media attention, a police force of 14 presided over a community of only 60 and collected around $400,000 in tickets annually. This comprised nearly all of the village's budget and nearly all went back into funding the police.