Real Estate Council of Austin hosted Leffingwell, whose second and final term in office expires at the end of the year. The mayor touted the city's strong growth—110 people per day, but warned that with such growth comes approximately 70 new cars on the road daily.

"Our traffic crisis—and I did say crisis—in Austin, Texas, has reached a point where it threatens to undermine what we've accomplished and what we can accomplish," Leffingwell told hundreds of community leaders and real estate industry representatives. "Our traffic problem isn't just an annoyance. It is a deadly serious threat to almost all of the things we have achieved and continue to strive toward."

The solution, Leffingwell said, is more options for Austin residents, starting with a proposed urban rail system from the future Austin Community College Highland campus to East Riverside Drive.

Austin voters will potentially vote in November to approve or deny a measure that would help fund the rail system. A similar initiative failed in 2000 in a metro-wide vote. Had the vote only been among Austin residents, Leffingwell said the measure would have passed. Instead, 14 years later the city remains without urban rail service, he said.

"Let me make it even simpler: rail or fail," he said during his speech.

Leffingwell acknowledged after his speech that urban rail will not erase Austin's traffic problems, but the added option will help provide an alternative to being stuck in vehicle traffic, he said.

Some of Austin's peer cities such as Denver, Seattle and San Diego have collectively invested $10 billion in rail transit the past 14 years, Leffingwell said, leaving Austin behind.

"Our competitors figured out the equation, and our competitors took action," he said. "Now the ball is about to be in our court one more time, and it will be up to us as a community to decide how to move forward."

During his speech, the mayor also defended the city's recent use of economic incentives to convince businesses such as athenahealth, Dropbox and Websense to come or expand in Austin. Since becoming mayor, the city has approved 11 incentive packages total, Leffingwell said, generating about $500 million in economic activity.

"Incentives have proven to be an effective tool to attract jobs and economic opportunity to Austin," he said.

Leffingwell also reaffirmed his efforts to help create an innovation zone in the northeast quadrant of downtown Austin near the future University of Texas medical school and teaching hospital. Additionally, the eastern edge of downtown will benefit from a Waller Creek redevelopment project that will take 28 acres out of the creek's floodplain.

"I believe we have the potential to remake what has been one of the most underutilized parts of downtown into a thriving new cluster of global commerce, culture, creativity and connectivity," Leffingwell said.