Until 1879, people bought milk as a bulk item, with the seller dispensing milk out of a keg or bucket into whatever jugs, pails or other containers the customers brought. That practice left a lot to be desired on the cleanliness front. Some dairies tried offering milk in fruit jars, perhaps because customers had started bringing the resealable containers to them to be filled. On April 8, 1879, Echo Farms Dairy introduced the first purpose-made milk bottles in New York City, delivering the milk from Litchfield, Connecticut.
Other dealers initially feared the expense of breakage, and some customers didn’t like the drugstore look of the containers. The new method of delivery eventually caught on. By the first decade of the 20th century, some cities were legally requiring that milk be delivered in glass bottles. Because of better sanitation and a lower bacteria count, thousands of children who otherwise may have died instead grew up to be healthy adults. Childhood diseases and deaths decreased after 1879 for a variety of reasons. Sanitary delivery of milk certainly was a contributing factor.
Because milk has a short shelf life, consumers used the contents quickly and returned them when they went to the market or when fresh milk was delivered to their doors by milkmen. The typical milk bottle made 22.5 round trips in the early 1900s before getting broken, lost or diverted by consumers to other purposes. The loss of bottles — as well as the expense of returning them to the bottling plant, washing and sterilizing them — contributed to the eventual abandonment of the glass bottle. Producers and consumers were also concerned about the health implications of transporting fresh milk in the same trucks right next to empty, unwashed bottles. All this led to the development of single-use containers. The earliest wax containers appeared in the 1890s. Shapes ranged from simple boxes to cylinders to cones to truncated pyramids, even ones that imitated the shape of a typical round glass bottle. What finally prevailed, in the 1940s, was a rectangular column design, with a small, round pull-up cap on a flat top piece. They were lightweight and compact, wasting little space in milk trucks.
Reference:
This Day in History 