Here's a posting to print-pubs-l that Mary Ann alerted me to...thanks!
"Many tourist bureaus throughout the U.S., including the Washington
Convention and Visitor's Bureau, have Websites or CDs available with photos
of buildings and sites in their state. In the case of the Washington
Bureau, anyone can use the images as long as the Washington Convention and
Visitor's Bureau (WC&VB) is given credit. Among the listings for other free
sources: http://www.firstgov.gov/Topics/Graphics_State.shtml
links to many individual state and local government sources including DC, the Convention & Tourism Corporation pressroom page,
http://www.washington.org/index.cfm?blnNavView=True
where 300 dpi jpeg downloads may be accessed directly by post or clients
upon registration from any country in the world. . . . . "