"Large Scale" USGS 1:24,000 (24K) Digital Elevation Models (which
correspond to 7.5 minute topographic quadrangle maps that cover about
6.3 x 8.7 miles) are available at 10 and 30 meter resolution. 30-meter
data sets are available for the entire US. Parts of the country have both
10 and 30 meter data (also known as 1/3-arc second and 1-arc second data,
respectively).
Even with JPEG compression, the difference between the two resolutions
is obvious in the images above. They show blufflands along the Mississippi
River in western Wisconsin. These DEMs are displayed in Global Mapper
at about 25% zoom with hill shading turned on.