Which OS X release began Apple's California place-name era in 2013?

Which OS X release began Apple's California place-name era in 2013? Mavericks. OS X Mavericks, version 10.9, was the first Apple desktop operating system named after a location in California.

Apple announced Mavericks at its Worldwide Developers Conference on June 10, 2013, and released it on October 22, 2013. The name refers to Mavericks, a renowned surfing area near Half Moon Bay on California's coast. It replaced the big-cat naming pattern used by releases such as Lion and Mountain Lion.

The new name reflected Apple's close ties to California and established a theme that continued for years. Yosemite, El Capitan, Sierra, High Sierra, Mojave, Catalina, Big Sur, and Sequoia all drew from California landscapes or landmarks. The sequence eventually expanded beyond California with later names such as Tahoe.

Mavericks was also notable because Apple made it available as a free upgrade through the Mac App Store. Its features included improved energy efficiency, Finder tabs, Tags, iBooks, and Maps. Sierra was much later, in 2016, and was the release that changed the product branding from OS X to macOS.