While the exact location of its invention isn't explicitly stated, it's widely believed to have happened in Dallas, Texas, where Graham worked as a secretary. She created the formula in her home kitchen, initially calling it "Mistake Out".
It's important to note that there are other brands of correction fluid, and the term "white-out" is often used generically. But Bette Nesmith Graham's "Mistake Out" was the pioneering product that laid the groundwork for modern correction fluid.