The joke may already have become widespread by the 1890s, when a variant version appeared in the magazine Potter's American Monthly:
Punning variations include "Why didn't the skeleton cross the road?" to which the answer is "Because he had no guts," or "He had no body to cross with him." "Why did the chicken cross the road halfway? To 'lay it on the line'." Or one might change the circumstances and the word "side", such as "Why did the chicken cross the playground? To get to the other slide."
Another class of variations, designed for written rather than oral transmission, employs parody by pretending to have notable individuals or institutions give characteristic answers to the question posed by the riddle. Variants on this theme are virtually endless.
Some variations work by elaborating on the circumstances of the event described by the joke. "Why did the chewing gum cross the road?" "Because it was stuck to the chicken's feet." Others employ anti-humor by giving a "rational" answer that is also absurd: "Why did the chicken cross the road?" "Because it had no frontal lobe." Other variants go for shock value: "Why did the dead baby cross the road?" "Because it was stapled to the chicken." In the movie Stripes, a reference to the joke occurs in an impromptu marching cadence: "Why did the chicken cross the road? To get from the left to the right!"
The joke is reportedly codified into law in at least one municipality. A Quitman, Georgia ordinance prohibits chickens from crossing the road.
In describing his experiences touring with The Residents on the laser disc documentary 20 Twisted Questions, illusionist Penn Jillette stated that one member of the band told this version: "Why did man invent God? To get to the other side." Here, "the other side" refers to the afterlife.