This image shows the well known Pigtail Bridge, located on Iron Mountain Road near the Mount Rushmore National Monument in South Dakota.
The description states:
Unique in design and construction, this pigtail bridge on the Iron Mountain Road enables the motorist to attain great altitude in a very short distance. IN the distance can be seen the faces of Mount Rushmore Memorial.
–A comparison of a more recent view of the bridge on the link above shows that the bridge and surrounding road are essentially unchanged. Moving from right to left the bridge curves towards the viewer in this perspective and then crosses under itself as it descends.
This card was used and is dated 26 June 1950.