The following are approximate tallies of current listings by county. These counts are based on entries in the National Register Information Database as of April 24, 2008[2] and new weekly listings posted since then on the National Register of Historic Places web site. There are frequent additions to the listings and occasional delistings and the counts here are approximate and not official.[3] Also, the counts in this table exclude boundary increase and decrease listings which only modify the area covered by an existing property or district, although carrying a separate National Register reference number.