This large photograph of the SR-71 Blackbird at the National Museum of the United States Air Force is an attention getter, showing the unconventional shape needed for trans-sonic flight. A new study by the American Association of Museums (AAM), the largest service organization in the museum field, shows that although more than two-thirds of America's museums experienced financial stress last year, institutions across the nation served a growing number of visitors. The study included all types and sizes of museums. Locally, the most dramatic increases in attendance come from the Air Force Museum in Fairborn, one of 481 museums that participated in the national study. 'The National Museum of the U.S. Air Force, like all Air Force organizations, is operating under strict financial constraints, but continues to attract an increasing number of visitors,' said Rob Bardua, a spokesman for the museum's public affairs division. 'Our attendance increased by more than 170,000 visitors from 2008 to 2009.'