The area was first populated at least 9,000 years ago, and was first recorded by Captain Robert FitzRoy during his voyage on HMS "Beagle" in the early 1830s (best known for its impact on the naturalist Charles Darwin). The municipality was established on July 24, 1948, as part of a nature conservation effort in the area during the administration of President Juan Perón. It was named for the Marquess Francisco Everardo Tilly y Paredes, a captain of the Spanish Armada who defeated Portuguese forces on the Río de la Plata, in 1795; is "roadstead" and also "inlet" in Spanish. The municipality is home to a growing population, which reached 6,208 in the 2001 Census, and has doubled every decade since 1980; its estimated population, per the provincial statistical bureau, was 9,226 in 2008. A beach resort city, Rada Tilly became one of the main recreational spots for visitors from nearby Comodoro Rivadavia, a city to the north. Many people living primarily in Comodoro Rivadavia also own second homes in Rada Tilly. These second homes serve the purpose of a lake home or a cabin for many residents; thus providing an escape from the busy city life of "el centro" in Comodoro.