PS Business Parks Inc. announced Tuesday that Maria R. Hawthorne has been promoted to president, effective immediately. Hawthorne, previously executive vice president and chief administrative officer at the real estate investment trust, takes over the title from Joseph D. Russell Jr. He has served as the company’s president since 2002 and its chief executive officer since 2003.

Hawthorne joined the company in an administrative role shortly out of Pomona College and has served 30 years in various management positions. She relocated from Southern California to Washington, D.C. where she grew the company’s largest division to 6.4 million square feet, comprised of 23 parks and 1,200 customers, generating more than $125 million in annual revenue. Most recently she was senior vice president in charge of the East Coast, supervising the firm’s launch into the Florida market in 2003 with a $215 million acquisition of a 3.4 million-square-foot industrial park.

She also recently led the re-entitlement process at the firm’s 45-acre Westpark Business Campus in the Tysons Corner submarket of Washington, D.C., which will include development of an approximately 400 unit multi-family project later this year.

Russell will continue as the company’s chief executive.

“I have had the pleasure of working with Maria for well over a decade, and time and again I have been impressed by her leadership qualities,” he said in a statement. “She has built and mentored strong teams, led important and complicated initiatives, while also finding ways of creating long-term shareholder value. I look forward to working with Maria in her new role.”

The company currently owns 28 million rentable square feet, with approximately 4,850 customers concentrated in six states. Shares closed down $1.79 or nearly 2.5 percent to $70.34 on the New York Stock Exchange.