A secondary source gives John's middle name as "Grove," but the one time he uses a middle initial in the census, it is "F."

A secondary source gives Mary's middle name as "Ann," but the two times her census records show a middle initial, it is "J," presumably standing for "Jane."

1.  Marriage Record:

2a.  1850 Census Index/Images (online at Ancestry.com; Image #14-15 of 28):  Bridgewater, Washtenaw Co., MI, pp. 347B-348A, 99/99, enumerated 20 Sep 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

Mear Strope	67	M		Weaver	200	Penn
Sarah	63	F				Penn
[next page]
John F	36	M				Penn
Mary	20	F				NY
Manerva	3	F				Mich

Michael & Sarah are John's parents.  John's middle initial is definitely, "F," not "G."

2b.  1850 Census Index/Images (online at Ancestry.com; Image #5 of 8):  Bridgewater, Washtenaw Co., MI, p. 343A/685, 31/31, enumerated 19 Sep 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

James Lyndon	57	M		Farmer	1000	Ireland
[James's wife and children]
John Stroup	36	M		Farmer		Penn
Mary	23	F				NY
Emeline	1	F				Mich
Harriet English	7	F				Mich

3.  1860 Census Indes/Images (online at Genealogy.com; Image #21 of 43):  Manchester P.O., Manchester Twp., Washtenaw Co., MI, Roll 563 (Book 1), p. 85, PN 21, 154/150, enumerated 8 Jun 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):¤•

John Strope	46	M		Farmer	1200	200	Penn
Mary J	34	F					NY
Minera E	12	F					Mich
John F	8	M					do
Ida E	4	F					do
Sarah	72	F					Penn

Sarah is John's mother.

4.  1870 Census Index/Images (online at Genealogy.com, Image #28 of 60):  Mason P.O., Vevay Twp., Ingham Co., MI, Roll 675 (Book 1), p. 279B, PN 28, 247/246, enumerated 25 Jun 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤•

Stroup John	57	M	W	Farmer	3500	700	New York
______ Mary	44	F	W	Keeping House			Michigan
______ John	17	M	W	At Home			"
______ Ida	15	F	W	At School			"
______ Elmer	9	M	W				"

John was born in PA and Mary in NY.

5.  1880 Census (indexed at FamilySearch.org; page image online at Ancestry.com, Image #2 of 25):  Vevay Twp., Ingham Co., MI, Roll 583, p. 496B, PN 2, SD 3, ED 137, enumerated 1/2 Jun 1880, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):¤•

1880:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	8	9	10	13	24	25	26
14	14	Stroup John	W	M	66			/	Farmer	PA	PA	PA
		______ Mary J	W	F	54	Wife		/	Keeping House	NY	Ireland	PA
		______ Elmer B	W	M	18	Son	/		at home	MI	PA	NY

6.  Email from Susan Patt, who shared this goldmine of information — thank you, Susan!

1889 Ingham Co MI Death records, Bk 2 p 54  John Stroup d 22 Aug. 1889 in Vevay of old age @75 yrs  Father-Michael and mother--Sarah  State of Michigan-return of Deaths in County of Ingham #1158  Date of Death--Aug 29 1889  John Stroup m w md age 75-3-6  pl of death: Vevay  cause: old age & (rupture?)  pl of Birth: Penn  Occ Farmer  Father Michael Stroup: res: Penn (sic)  Mother Sarah Stroup: res: Penn (sic)  Rec. May 12 1890  NOTE: dif. death date  Ingham County Democrat  Mason, Michigan Thursday, August 29, 1889  p5 col 3  JOHN STROUP, an old and respected citizen of Alaiedon township, died on Thursday last, after a lingering illness. Deceased was born in Union county, Pa., in 1814.  In 1836 he moved to Michigan, locating in Washtenaw county, where he remained until 1865, when he located on the farm on which he died.  His wife and four children--Mrs. F. M. Briggs of Grand Rapids, Mrs. J. E. (sic) Irish and Elmer E., and John L. Stroup, survive him. Funeral services were held at the residence Saturday afternoon, Rev. DeLamarter officiating. The remains of deceased, who was looked upon as a truly good man, were interred in the city cemetery.  Ingham County, Michigan Vital Records  Recorded by Lansing Chapter DAR  Maple Grove Cemetery  Mason, Ingham County, Michigan  p 228  Stroup John d 1889 a. 75y  Stroup, Mary w. John d. 1894 a. 68y

7.  Birthdate calculated using Ben Buckner's Birthdate Calculator.

Name	Deathdate	Age at Death	Result
John Stroup	29 Aug 1889	6d 3m 75y	23 May 1814
(Calculated birthdates should always be prefaced with "ca." — you can't be certain the person who calculated their age did it correctly.)

8.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).