The Lamar Boulevard Bridge is a historic bridge carrying Lamar Boulevard (Loop 343) over Lady Bird Lake in downtown Austin, Texas, United States. The bridge features six open spandrel concrete arches and carries thousands of vehicles daily across the river. Completed in 1942, the Lamar Boulevard Bridge was the second permanent bridge to cross the Colorado River after the Congress Avenue Bridge. The bridge was added to the National Register of Historic Places on July 7, 1994. The Lamar Boulevard bridge that crosses Lady Bird Lake exceeds acceptable daily traffic volumes by more than double, according to a study by the Downtown Austin Alliance. The bridge allows for about 20,000 cars per day, but currently nearly 45,000 vehicles use the bridge everyday.