BOULDER — Footwear brand Birkenstock has opened a Boulder retail location at 1750 29th St., Suite 1042, in the Twenty Ninth Street shopping district. The Boulder store is the German sandal-maker’s 21st location in the United States. The company has also opened a new store in West Palm Beach, Florida. “Opening our doors in Boulder and West Palm Beach is a meaningful step in Birkenstock Americas’ retail journey. We’re proud to bring the Birkenstock experience to both and look forward to becoming part of their communities,” Birkenstock president David Kahan said in the release.