The Antique Site
"Antique" can refer to almost any old object that has value due to its age, aesthetic appeal, condition, rarity, and/or historicalsignificance.
But it's not always simple deciding what is or is not an antique. In the 1930s, antiques were considered artwork, and thus could be brought into the United States duty-free — so everyone wanted to call every old item an antique.
U.S. Customs Steps In
The U.S. Customs Office surveyed antique dealers, and concluded that antiques were objects made before the development of mass production in the 1830s. Since that definining moment — mass production — was 100 years in the past, the customs office decided that an antique was something made more than 100 years ago. Duty was collected on objects less than 100 years old, but items more than 100 years old were still duty-free.
Antiques vs. Collectibles
That definition is still in use today, and is used by collectors and dealers to distinguish between true antiques and collectibles.