Current day milkshakes have a very interesting history behind them. In fact, the beginning of the milkshake can be traced back to 1850, where eggnog drinks topped with frothy alcohol were served as milkshake. Of course it was nowhere near the current day milkshakes at all.
It is true that there is absolutely no resemblance between the old alcohol mixtures to current day milkshake. The milkshakes that we love have one ingredient ice cream that transforms it into a smooth and creamy drink. Ice creams came to be added with milkshakes only around 1920s.
The milkshake owes its origin to a Walgreen’s fountain manager who concocted a new mixture as a part of an experiment. He was trying to make something new to serve his customers when he picked up a few scoops of ice cream and put them into the mixer, which had malt milk leftovers and was born the creamy rich liquid that has engaged our fantasy for decades.