These 19,840 acres of desert and mountains became the first regional park in the Maricopa County Park System in 1954. Located near the meeting of the Gila and Agua Fria Rivers in the southwest Valley, the park includes a large wetland, or riparian, area. The majority of the park remains pristine desert, very similar in appearance to the landscape seen by the first settlers and explorers. The Sierra Estrella range, or Star Mountains, was once within the Mexican border, and remained so until the Gadsden Purchase in 1853. Today, many amenities are available to visitors, including the only grass picnic area in the Maricopa County Park System.