The coverages originally were posted in November 1997 (NAD 27). A NAD83 version was posted in March 2000.
The coverages were updated significantly in March 2001 to bring the
coverage names and sucodes more in line with current netcode
conventions. (For example, lsuslus1 is now lsuslusag1, and gaflluscr
is now gaflluscr1.) One coverage corresponds to each netcode, which
means that some coverages are duplicates if one boundary represents
more than one network.