Hi Sharon, I did find the Pierce family on the Censuses after using the Pierce spelling. A George G. Pierce d. Multnomah County, 13 Aug 1983, per death cert #83-13655; age=69, b. 27 Jan 1914; spouse=Mary. Source: OR Death Index.
A George Pierce whose last residence was Portland, Multnomah Co. was b. 27 Jan 1914. His last benefit check was mailed to Portland. He d. Aug 1983. His soc. sec. # was assigned in OR in 1961. Source: Social Security Death Index which anyone can access at no charge.
I'd try to get a copy of his obituary which should tell you where his brothers were living at the time of his death. Contact University Oregon http://libweb.uoregon.edu/general/gethelp.htmlhttp://libweb.uoregon.edu/general/gethelp.html or OR Library System www.oregonlibraries.net/.
I didn't find anything for John or Walter. Successful Hunting!