Truck drivers who transport milk from a farm to a milk processing plant are also known as milkmen. Raw milk is picked up daily, or every other day.
Milk deliveries frequently occur in the morning and it is not uncommon for milkmen to deliver products other than milk such as eggs, cream, cheese, butter, yogurt or soft drinks.
Originally, milk needed to be delivered to houses daily since the lack of good refrigeration meant it would quickly spoil. The near-ubiquity of refrigerators in homes in the developed world, as well as improved packaging, has decreased the need for frequent milk delivery over the past half-century and made the trade shrink in many localities sometimes to just 3 days a week and disappear totally in others. Additionally, milk delivery incurs a small cost on the price of dairy products that is increasingly difficult to justify and leaves delivered milk in a position where it is vulnerable to theft.
In some areas apartments would have small milk delivery doors. A small wooden cabinet inside of the apartment, built into the exterior wall, would have doors on both sides, latched but not locked. Milk or groceries could be placed in the box by a milkman, and collected by the homeowner.