Terratracer has National Agricultural Imagery Program (NAIP) natural color aerial photography data for many of the agricultural areas of te USA in 50cm - 2m resolution for 2006-2014. The 2006 NAIP is a statewide coverage. The images are grouped together by county. They can be ordered from this site as a large set of.zip files on a HDD (Hard Drive Device).
The .zip files contain a compressed Mr.Sid image. The date the photography was flown for 2003 and 2004 is in the IDAT field of the compressed county mosaic index. For the 2006 imagery the NAIP2006_Index shapefile contains the date the image was flown. The images have a UTM NAD83 meters projection.