apple-pie order

A very organized and neat state. Don't worry, we'll find that file—Elaine keeps all the records in apple-pie order.

Extreme neatness, as in David keeps his financial records in apple-pie order. This term is generally believed to be an English corruption of the French nappes pliées, "neatly folded linen." [Early 1600s]

Very neat. One writer speculates that the term originated in the practice of New England housewives meticulously arranging apple slices on a pie crust. However, more likely it was a British corruption of the French nappes pliées, neat as “folded linen,” from the early seventeenth century. By the time Dickens used it in Our Mutual Friend (1865) it was already a cliché.

Neat, orderly, well organized. Although the exact derivation is unknown, folk etymology (which word detectives fall back on when there's nothing more authoritative) suggests the following: New England housewives were so organized at slicing apples for their pies, laying out the slices inside the crust, and then making sure that the top and bottom crusts were evenly pinched together that their meticulousness gave rise to the phrase.