The following companies make all their printing/writing paper alkaline:
Canadian Pacific Forest Products
Ecusta (part of Glatfelter)
Grays Harbor (part of IP/Hammermill)
Miami (part of Cross Pointe)
Potsdam (part of Little Rapids)
Ward (part of IP/ Strathmore)
Weston (part of Crane)
George A. Whiting
Parsons Paper (part of NVF) and Warren (part of Scott) make most of their paper alkaline.
There are many more companies that make one or more grades alkaline, and there are also quite a few paper convertors and distributors who market one or more alkaline papers under their own brand name.