Phoenix-based Lewis and Roca, a 170-attorney firm with offices in Nevada, Arizona and New Mexico, is merging with one of Nevada’s oldest firms, Beckley Singleton.

The firm will do business under the name Lewis and Roca, and it will be one of the largest in Nevada, with 57 attorneys practicing in the state and 200 attorneys firm wide. The merger will be effective as of Aug. 1, 2007.