San Antonio is known for the Riverwalk, but a comprehensive new study shows exactly how important the state's number two tourist attraction is for the city's economy, 1200 WOAI news reports.

Casandra Matej, who heads the San Antonio Convention and Visitors Bureau, says the Riverwalk attracted 11.5 million people last year. resulting in a $3 billion economic impact, and 21,000 jobs.

"We were all surprise just how significant and just how large the economic impact was to the community,"  Matej told 1200 WOAI's Michael Board.

 It is the first comprehensive study of the impact of the Riverwalk on the local economy, and the study shows in addition to being a key element of the city's tourism infrastructure, it also improves the quality of life for locals and businesses, enhancing the vibrancy of the city's downtown.

The Riverwalk began life as a depression-era Works Project Administration project in the late 1930s, pioneered by Mayor Maury Maverick and legendary architect Robert Hugman.  The Riverwalk has grown over the years, stretching to the new Convention Center for Hemisfair 68, and recently extended north and south through the Mission and Museum Reach, which turned the Riverwalk into a biking and kayaking center.

But Matej says it is the tree lines, below ground stretch of shops, restaurants, and bars which remains the iconic center of San Antonio.

"I think that we were pleasantly surprised that it is a much bigger impact than we once thought," she said.

Another surprising finding of the study, 2.2 million Riverwalk visitors in 2013 were local San Antonio residents.

"It does kind of defy that myth that the Riverwalk is just for tourists," Matej said.

Lori Houston, who heads the city's Office of Center City Development, says the study will help officials plan the evolution of downtown, especially the long delayed redevelopment of Alamo Plaza.

"The Riverwalk is a historic landmark for our city, and the unique character it brings to downtown is a key attraction for new development in the center city," she said.  The study is a valuable tool as we can now quantify the economic impact of our river and share this information with our existing and future downtown stakeholders."