From the OHS PC Database, derived from A Guide to North America Organ Builders by David H. Fox (Organ Historical Society, 1991). Updated Feb 7, 2016 with information from sources listed below. —

John P. Hunter was partner with Albert G. Hunter (presumed to be his older brother) as A.G. & J.P. Hunter of Philadelphia¹ from circa 1830 until Albert's death in 1867². John continued the firm, and was joined by his sons John R. and Newton by 1880, doing business as J. P. Hunter & Sons³ of Philadelphia, PA. John P. Hunter died around 1902, John R. continued the firm, as Newton died at 28, predeceasing his father.⁴ After John R. Hunter's death, the business merged with Bernard Mudler's firm, it was incorporated as Mudler-Hunter in 1921⁵ although the actual merger likely happened year before that.

Sources:

1. OHS Database Entry "A. G. & J. P. Hunter".


2. Philadelphia City Death Certificate for Albert G. Hunter.


3. John Speller, Pipe Chat, February 1, 2008 (see paragraph below for full text).


4. Philadelphia City Death Certificate for Newton Hunter.


5. Speller, Pipe Chat.

From Organ Database Builders editor Stephen Hall, September 13, 2019. —

Albert G. and John P. Hunter formed a company named A.G. & J.P. Hunter which traded in Philadelphia in the 1860's and 1870's. By 1880 this had morphed into J.P. Hunter & Sons. There does not seem to be any connection with the London, England firm of A. Hunter & Son. Bernard Mudler was also active as an organbuilder in Philadelphia from about 1870 onwards. The Mudler-Hunter firm was incorporated in 1921 and seems to have resulted from a merger of these two previous firms. [February 1, 2008]

Source: John Speller, Pipe-Chat, last accessed 2015, http://www.pipechat.org/.