Cox Smith Matthews, the largest firm based in San Antonio, will merge with Detroit-based Dykema Gossett on May 1, creating a firm with about 450 lawyers in 15 offices. Initially, the firm will be known as Dykema Cox Smith in Texas.

Deborah Williamson, managing director of Cox Smith, said the combination with Dykema gives her 114-lawyer firm the means to better serve clients outside Texas, where it has offices in Austin, Dallas, El Paso, McAllen and San Antonio.