Sonic Corp. today announced the opening of the 3500th drive-in, an occasion that highlights another significant landmark in the growth of the Sonic brand.

Earlier this month, Sonic’ss Chairman and CEO Cliff Hudson joined franchisee John Cywinski in Algonquin, Illinois, to celebrate the opening of the drive-in that has been ceremonially designated as the 3,500th Sonic Drive-In.

To commemorate the occasion, the Village of Algonquin Chamber of Commerce, Cywinski Enterprises and Sonic Corp., held a ribbon cutting at the drive-in.

“Despite Chicago’s winter weather, we are pleased by the warm welcome for Sonic from the community and are pleased to have served more than 20,000 customers in our first four weeks of business,” said John Cywinski, Cywinski Enterprises and Algonquin franchisee. “We are proud to open the 3,500th drive-in in Algonquin and look forward to delivering the wonderfully unique Sonic experience for years to come.”

The drive-in officially opened December 4, 2008.

Commenting on the significance of the event, Hudson added, “For many reasons, this is a very special event for all of us at Sonic. We are delighted that this milestone occasion occurred in one of our newest Sonic markets—Chicago.”

“For more than 50 years, we’ve witnessed the continued growth of SONIC,” Hudson continued. “Our company crossed the 2,000 drive-in mark in 1999 and the 3,000 drive-in mark in 2005. Now, three years later, we’ve reached 3,500 drive-ins. This remarkable growth, which has taken us from coast to coast, has created so many opportunities for all those affiliated with our brand. For this, we are thankful to all our operators, and especially our franchisees.”

Chicago-based Cywinski Enterprises is one of three teams developing in the Chicago market. Cywinski Enterprises led by John Cywinski has plans to develop the North/Northwest Chicago suburbs, including Lake and McHenry Counties.

Boom Enterprises, another Chicago-area franchise group, will develop the Western suburbs of Chicago in Kane, Dupage, and Northwest Cook counties. The franchise group opened Chicago’s first SONIC Drive-In at 2974 Kirk Rd. in Aurora last August.

Sonic Restaurants, Inc. (SRI), the company’s restaurant-operating subsidiary is the principal owner of the new Sonic Drive-In at 4023 W 167th Street in Country Club Hills, which opened November. 10. SRI has additional plans to further develop the South suburbs.