In what is very likely to surprise most people, kettle corn as we know it today has been around since at least the early 18th century. It might even be older than that, and could have first been invented as early as during the introduction of granulated sugar and salt to the first American colonies. It's origin is obviously rooted within the mainland United States, and very possibly to the area in and around the state of Pennsylvania. It's occasionally stated that the official date of discovery is 1776, the same year that the United States was officially formed, however it's likely older than that. The first known mention of kettle corn within documents, comes from the journals of Dutch settlers, who arrived from their native European homeland to form small Dutch communities in Pennsylvania. According to these journals, kettle corn was served as a special treat during various festivals and outdoor fairs, similar to how it is made and served in this day and age.
During it's first rise in popularity, most of the kettle corn was cooked usually without oil. Once done, it was garnished with bees honey and salt, which were two ingredients with relative abundance during that time period. It wasn't until the mid to late 18th century, that the use of granulated sugar began to overtake bees honey as the main kettle corn sweetener. The reasons for this change are obvious to anyone who has ever attempted to create kettle corn with honey, a very difficult task in comparison to granulated sugar. With sugar you get a nice caramelization process that occurs as the granulates melt down, and usually this process will not cause the popped popcorn to get soggy or dampened. Sugar can melt and solidify nicely within any properly designed kettle, however liquid bees honey tends to take a much colder temperature change to caramelize, especially the more altered varieties. It can be done however, though it's difficult to get it right.
Kettle corn enjoyed a very popular 18th and 19th century, however it's popularity began to fade away during the early 20th century. It is not known exactly why this fading of interest took place, however some have suggested that it was due to a huge burst in innovation of snack foods that occurred during this time, and that the market was simply oversaturated with a variety of new goods. Once all the new hoopla over animal crackers, caramel corn, cookies, and new soda pops began to fade itself, kettle corn started to recover in popularity around the 1950s, and has been a growing snack ever since then. The methods of cooking the kettle corn have also greatly improved over the last several decades, which has helped kettle corn hold it's market share in the overall snack foods market. It is thought that the kettle corn of previous centuries was not as consistently delicious as it is today, as they couldn't use propane or gas heating sources.
In today's day and age, kettle corn is huge. You can find a kettle corn booth at almost every single fair and festival in every major city across the United States. It's also growing in popularity outside of the US for the first time ever. I have personally witnessed kettle corn booths in Tokyo, Paris, London, Prague, Warsaw, and various other places in the world. The last two decades have also seen a huge growth in the corporate expansion in kettle corn snacks, as it becomes available as a prepackaged snack food, served straight out of a bag just like potato chips. As somewhat of a kettle corn puritan, I am not particularly warm towards the idea of mass produced prepackaged kettle corn, as it's just not the same species of kettle corn as the fresh made variety, and likely isn't even made in a kettle to begin with. The mass produced variety could also negatively effect the public's interest in the traditional made variety, as it becomes overly available.