The Mousetrap Is the Most-Patented Device in American History. Almost None of Them Work.

US528671 was granted to William C. Hooker of Abingdon, Illinois, on November 6, 1894. It describes the snap trap: a flat wooden base, a coiled spring, a pivoting metal bar, and a trigger holding it under tension until something disturbs the bait.

You have seen it. It has barely changed in a hundred and thirty years. It costs about a quarter to make.

And it sits on top of one of the strangest statistics in the entire patent archive.

Four thousand attempts

The United States Patent and Trademark Office has granted more than 4,400 patents for mousetraps, and has rejected several thousand more applications. It is, by a wide margin, the most-patented device in American history — more than the telephone, the engine, or the chair.

Of those thousands of granted patents, the number that ever earned their inventors any meaningful money is usually estimated at around twenty.

The traps that failed are a genuine wonder to page through. There are traps that drown, electrocute, glue, poison, crush, cage, and launch. There are traps with elaborate multi-chamber mazes, traps disguised as furniture, traps with automatic resetting mechanisms, traps that dispose of the body, traps operated by falling weights, and traps of such mechanical complexity that they resemble small factories.

Why the simple one wins

The reason the 1894 design beats them all is economic, not mechanical.

A mousetrap is a disposable commodity that competes on price. It must cost pennies, because a homeowner needs several and considers each one worthless after use. Hooker's design has four parts, requires no assembly skill, is stamped and cut from the cheapest possible materials, and works well enough.

Every "better" mousetrap fails on the same axis: it is better at catching mice and much worse at being cheap. A trap that costs eight dollars and catches mice more humanely and resets itself is a superior machine and an inferior product, because the customer will not pay eight dollars to solve a problem they think is worth twenty-five cents.

The proverb is wrong

The saying — build a better mousetrap and the world will beat a path to your door — is usually attributed, loosely, to Ralph Waldo Emerson, and the mousetrap archive is the most thorough refutation of it ever assembled.

Thousands of people did build a better mousetrap. The world did not beat a path to their door. It kept buying the cheap wooden one, because "better" in engineering and "better" in the market are different words that happen to be spelled the same.

The patent record contains 4,400 demonstrations of this, which makes the humble snap trap one of the most instructive objects in it.

See the original

The full text and figures of US528671 are on patents.us.