Olof Pedersén, Archives and Libraries in the Ancient Near East 1500-300 B.C. (1998), remains the most comprehensive survey of the earliest western archives and libraries that I have seen, as of February 2013. It contains numerous schematic diagrams of ancient building layouts on which it identifies the location of each library or archive found. With a few exceptions, it does not discuss or attempt to summarize the contents of any archive or library covered.
1. Pedersén's study describes 253 archives and libraries from 51 different cities, of which 125 archives and libraries date from 1500-1000 BCE and 128 to 1000-300 BCE. "Since many of the very early excavations did not properly document the find-spots of tablets, it is probable that some additional archives or libraries from this period have been unearthed. . . ." (p. 238)
2. "Most of the cities or towns where archives or libraries have been unearthed were cities of medium or major size. Only rarely has material been found in smaller towns. . . ; it is unclear whether this is due to lack of written documentation in rural areas or only a consequence of a limited number of excavations of smaller settlements.
3. "Several of the archives and libraries, expecially the larger ones, were apparently placed upon wooden shelves. Evidence of wooden shelves is proposed to exist for a limited number of official archives (Tapigga 1, Harbe1), and has been assumed elsewhere (e.g., Nineveh 2). There is, however, a lack of evidence in many sites indicating the use of wooden shelves, probably due to the perishable nature of wood and a lack of sounder achaeological methodology during the earlier excavations. Sometimes the shelves were constructed of brick or designed as niches in the walls. Such imperishable shelves have been preserved in the some libraries (Dur-Sarrukin 1 and 2, Sippar 2). The temple library in Sippar is the oldest library in history found with literary texts still standing in their original position on the shelves" (p. 244).
4. "The largest archives and libraries consist of between 1,000 and 30,000 texts. There are at least 16, perhaps even 21, archives or libraries of such size. They represent six or eight percent of the total number of 253 archives and libraries discussed here. The largest archive is the Neo-Babylonian administrative archive from the Samas temple (Sippar 1), comprising about 30,000 texts." (pp. 244-45).