(Photo by Mark Brodie-KJZZ)

Scottsdale's McDowell Sonoran Preserve.

Scottsdale has added more than 2,300 acres to its McDowell Sonoran Preserve. The city bought the land for more than $21 million at a state land auction on Tuesday.

Scottsdale was the only bidder. Including the newly-acquired land, the city’s preserve includes around 30,000 acres, more than 47 square miles. The city said its ultimate goal is to preserve about 34,000 acres. That is nearly a third of Scottsdale’s land area.

The land acquired Tuesday includes the majority of ridgeline in the southern McDowell Mountains, generally north of the Thunderbird Road alignment, south of the Bell Road alignment, east of the 120th Street alignment and west of the 136th Street alignment.