----------------------------Original message---------------------------- I recently shifted our USGS topographic set to accommodate superceding additions. The shift was made by measuring random groups of 100 maps with calipers, applying the average to the space available, and calipering the hundred map average as the shift proceded. The method worked well and about 90,000 maps were moved quickly and evenly distributed. The tolerance of our 'average' left about 2.25 extra inches at the end of the shift. I am now concerned with future growth. Is it appropriate to anticipate an even distribution in the creation of superceding topos by USGS? Or, should one expect that some individual states/ locals will be more quickly superceded than others? Thanks! R.Balliot