"This system of 50 symbol signs was designed for use at the crossroads of modern life: in airports and other transportation hubs and at large international events. Produced through a collaboration between the AIGA and the U.S. Department of Transportation, they are an example of how public-minded designers can address a universal communication need.
Prior to this effort, numerous international, national and local organizations had devised symbols to guide passengers and pedestrians through transportation facilities and other sites of international exchange. While effective individual symbols had been designed, there was no system of signs that communicated the required range of complex messages, addressed people of different ages and cultures and were clearly legible at a distance.
To develop such a system, AIGA and D.O.T. compiled an inventory of symbol systems that had been used in various locations worldwide, from airports and train stations to the Olympic Games. AIGA appointed a committee of five leading designers of environmental graphics, who evaluated the symbols and made recommendations for adapting or redesigning them. Based on their conclusions, a team of AIGA member designers produced the symbols.
A first set of 34 symbols was published in 1974, and received one of the first Presidential Design Awards; 16 more symbols were added in 1979. These copyright-free symbols have become the standard for off-the-shelf symbols in the catalogues of U.S. sign companies. They are now available on the web for the first time."
No explicit license for these particular images, but implied they are in the public domain. (See last paragraph above.)
Available separately in EPS and GIF formats on AIGA site.