There is nowhere near enough room for 100,000 in-ground graves.  In fact, because they were running out of ground space, there is a cutoff date for veterans eligible for in-ground burial, (I think it is sometime around the Vietnam Era).  There are some other rules for in-ground too...maybe KIA eligible too, etc. Most veterans are now cremated and interned in the Columbarium, a huge mausoleum complex.