— born in Oakfield Twp., Kent Co., MI:
5.  Mary J. STROUP, b. 1850/1
6.  Harriet STROUP, b. 1851/2
7.  Antoinette / Antonette / Annette STROUP, b. 1853/4

1.  Marriage Record:

2.  1850 Census Index/Images (online at Ancestry.com; Image #1 of 9):  Town of Oakfield, Kent Co., MI, Roll M432_353 (Book 1), p. 313B, 347/347, enumerated 1 Nov 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

Henry Stroup	33	M		Farmer	400	Penn
Mary Stroup	38	F				N J
George ? Stroup	5	M				Mich
Henry Stroup	3	M				Mich
Osker Stroup	1	M				Mich
Edgar Stroup	?	M				Mich

3.  1860 Census Index/Images (online at Genealogy.com, Image #22 of 28):  Oakfield P.O., Oakfield Twp., Kent Co., MI, Roll 550 (Book 1), p. 568, PN 22, 173/159, enumerated 6 Jun 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):¤•

Henry Strope	43	M		Farmer	700	200	Pennsylvania
Mary     "	47	F					New Jersey
George   "	15	M					Michigan
Henry    "	13	M					"
Edgar    "	11	M					"
Oscar    "	11	M					"
Mary J   "	9	F					"
Harriet  "	8	F					"
Antanett "	6	F					"

Edgar and Oscar are connected with lines presumably indicating they are twins.

4a.  1870 Census Index/Images (online at Genealogy.com, Image #4 of 16):  Cedar Springs P.O., Spencer Twp., Kent Co., MI, Roll 682 (Book 1), p. 582B, PN 4, 27/27, enumerated 26 Jul 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤•

Strope Henry	55	M	W	Farmer	2000		Pennsylvania
_____ Mary	60	F	W	Keeping House			New Jersey
______ Oscar	21	M	W	Farm Laborer			Michigan
______ Harriet	18	F	W	No Ocupation			Michigan
______ Annett	16	F	W	No Ocupation			Michigan
______ Edgar	21	M	W	Farm Laborer	300		Michigan

Listed two households from son, Henry STROUP/STROPE.

4b.  1870 Census Index/Images (online at Genealogy.com, Image #5-6  of 16):  Cedar Springs P.O., Spencer Twp., Kent Co., MI, Roll 682 (Book 1), pp. 583A-583B, PN 5-6, 45/45, enumerated 26 Jul 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤•

Young Eugene	21	M	W	Works in Shingle Mill		100	Prusia
_____ Clara	16	F	W	Keeping House			Michigan
[next page]
Strope George	24	M	W	??? Shingle Mill		750	Michigan
McCleland James	20	M	W	Works in Shingle Mill			Michigan
Strope Harriet	18	F	W	Domestic Servant			Michigan

5.  1880 Census (indexed at FamilySearch.org; page image online at Ancestry.com, Image #3 of 26):  Spencer Twp., Kent Co., MI, Roll T9-0587 (Book 1), p. 401C, PN 3, SD 2, ED 110, enumerated 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
28	28	Stroup Henry	W	M	65			/	Farmer	PA	Ger	Ger
		______ Mary	W	F	69	Wife		/	Keeping House	NJ	NJ	NJ
		______ Antonette	W	F	26	Dau	/		Helps at home	MI	PA	NJ

Listed three households from presumed widow, Emily J. (__?__) STROUP. 

6.  Anon.  1881.  The History of Kent County, Michigan.  Chas C. Chapman & Co., Chicago (extracted biographies online at the Kent County MIGenWeb site; transcribed by "JKG").  On p. 1357:

Henry Stroup was born in 1815, in Pennsylvania, and was brought up and educated in Seneca Co., N.Y.; is son of Michael and Sarah (Graves) Stroup, natives of Pennsylvania, of English descent.  The great-grandmother of Mr. Stroup, Amanda Whitmore, lived to the enormous age of 126 years.  His life has been one of varied occupations; he was a driver on the canal seven years and was engaged about 20 years running logs on Flat river, and in 1847 he settled on 80 acres of land on sec. 34, which he located from the Government at the period when all of Spencer was an unbroken forest.  He was married in 1841 to Mary Sandford, born in New York, of Scotch and English descent.  They have five children.  Mr. Stroup is a Rebublican, and has held the office of Highway Commissioner, Justice of the Peace and other official positions.

Sarah GRAVES may have been of English descent, but Michael STRAUB/STROUP was German.

7.  Anon.  1870.  History and Directory of Kent County, Michigan, Containing a History of Each Township and the City of Grand Rapids.  Dillenback & Leavitt Publ., Grand Rapids, MI (online at the Kent County MIGenWeb site; transcribed by Jennifer Godwin):

SPENCER The township of Spencer is situated in the northeast corner of the county, and is bounded on the north by the township of Maple Valley, Montcalm County, on the east by Montcalm, Montcalm County, on the south by Oakfield, and on the west by Nelson.  The first white inhabitant of Spencer was an old trapper, by the name of Lincoln.  He had a shanty on the bank of the lake of that name, and there he lived, Boon like, for a number of years.  The first regular settler of the township was Cyrus B. Thomas, who located in the summer of 1846.  Henry Stroup, the second settler, located in January 1848.  Both of these settled on a plain in the southeastern part of the township, near the Oakfield line; and, for a number of years, were the only actual settlers...