Milk bottle caps pretty much disappeared when they stopped making glass milk bottles which was over 30 years ago in most parts of the country. They have been popular for years with dairy and milk bottle collectors.
The vast majority of the bottle caps we sell are unused old stock found in old bottling plants and dairies. It is not unusual to find a lot of unused old cork lined soda caps in an old plant as they often had cases leftover when they changed from cork to plastic. The same with the dairies. When they went to plastic screw on bottles, they often had plenty of milk caps left they never used.
