The original settlers to Oak Glen were the Cahuilla and the Serrano. They harvested acorns for survival in Oak Glen. The unique climate and elevation was perfect for growing large black acorns, a favorite among the locals. The evidence can still be found along the streambeds where the acorns were leached over 100 years ago. Although the main crop of Oak Glen was apples since the 1940s, it hasn't always been Oak Glen's only crop. The potato along with many other crops, were grown in Oak Glen since the 1890s. After several farms began to sell apples individually to visitors, along with homemade apple pies, fresh apple cider and delicious apple butter from roadside stands Oak Glen became an apple boom town overnight. The export trade has since virtually disappeared, and growers now earn much of their revenue from visitors who are allowed to pick the apples directly from the trees to insure freshness and the best quality. Today many of the heirloom varieties still exist today even though many of them have been since lost in time. Such varieties, which are grown only in Oak Glen, as well as many heirloom varieties no longer commercially available or are hard to find, such as the Arkansas Black and the Glen Seedling favorites among many.