By the way, I'm pretty sure none of the actual AWS datacenters are in Reston proper. They are in Ashburn and other more sparse suburbs.
Source: I live in the DC area and regularly visit Reston and Herndon. There are large AWS offices in Herndon but not so many datacenters. Real estate in Reston is pretty expensive.
Pretty sure you are right. The physical AWS data centers I know of in Reston area are:
4 DCs on Smith Switch Rd in Ashburn, VA
2 DCs (IAD54 and IAD67) elsewhere in Ashburn, VA
3 DCs on West Severn Way in Sterling, VA
3 DCs on Dulles Summit Ct in Sterling, VA
2 DCs on Prologis Dr in Sterling, VA
2 DCs on Relocation Dr in Sterling, VA
2 DCs (IAD69 and IAD76) elsewhere in Sterling, VA
1 DC in South Riding, VA
4 DCs on Westfax Drive in Chantilly, VA
3 DCs on Mason King Ct in Manassas, VA
2 DCs elsewhere in Manassas, VA