Duckburg, home of Donald Duck and company, is possibly the only Disney city whose location has been pinpointed. While most Duck artists have generally avoided placing Duckburg and its state of Calisota in any spot in particular, Don Rosa located the city on the north coast of California, about where the town of Eureka is in the real world. This means, in the Duck version of Earth, the northernmost part of California (at least) is actually the state of Calisota.
Interestingly, Calisota almost had a real life counterpart. In 1941, Gilbert Gable, mayor of Port Orford, Oregon, announced that the four southwesternmost counties of Oregon (Curry, Josephine, Jackson, and Klamath) should join forces with the three northernmost counties of California (Del Norte, Siskiyou and Modoc) and create the new state of Jefferson. Gable made this proposal mostly as a publicity stunt to draw attention to the poor state of the state roads along the Oregon-California border. However, people throughout the region liked the idea, believing the existing state governments as indifferent to their needs. Siskiyou county especially embraced the idea as its county seat, Yreka, was chosen as the provisional capital. However, the death of Gilbert Gable and the bombing of Pearl Harbor in December of that year put the brakes on any further plans for Jefferson.
(Eureka is the county seat of California's Humboldt County which borders Del Norte County's southern border as well as the coast of the Pacific Ocean.)