Some secondary sources give him middle name, "Sylvester," but he is Sylvanus in both the 1860 and 1870 censuses.  Secondary sources show him as having died in Madison Co., MO, but he was living in Wayne Co. in the 1910 census, and his widow was still living there in the 1920 census, so a death in Wayne Co. (and a burial in adjacent Madison Co.) seems more likely.

— born in MO, either in Fillmore Twp., Bollinger Co., MO, or Cedar Creek Twp., Wayne Co., MO:
2.  Ida Elizabeth STROUP, b. Jan 1882
3.  Verda Victoria "Birdie" STROUP, b. 14 Sep 1884
4.  [Harriet?] "Hattie" Jane STROUP, b. Jul 1886; m. John Thomas DORSEY 
5.  Monroe H. STROUP, b. Mar 1889
6.  Rosa A. STROUP, b. Sep 1891
7.  William L. A. STROUP, b. Nov 1892

1.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

Stanhope Sylvester Stroup Birth: 28 Dec 1855, Missouri Death: 07 Mar 1916, Madison, Missouri Spouse: Mary Elizabeth Wright Source: patron submission

He is "Sylvanus" in both the 1850 and 1860 censuses.  Mary is "Mary Eliza" on her tombstone.

2.  LDS.  Family Search: Internet Genealogy Service: Pedigree Resource File (index to CDs, online at FamilySearch.org).

Stanhope Sylvester STROUP Birth: 28 Dec 1855; Death: 7 Mar 1916; Burial: Dorris Cem. Madison Co, MO Father: William Henry STROUP; Mother: Nancy Adeline SITZES Spouse: Mary WRIGHT Birth: 20 Nov 1857; Death: 29 Sep 1937; Burial: Dorris Cem. Madison Co, MO Source: patron submission

Stanhope's parents are definitely not William & Nancy (SITZES) STROUP; William is Stanhope's uncle. 

3.  1860 Census Every-Name-Index/Images (online at Ancestry.com, Image #2 of 8):  Buchanan P.O., Fillmore Twp., Bollinger Co., MO, Roll M653_608, p. 624, PN 176, 1238/1236, enumerated July 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):¤•

Andrew J Dellinger	20	M		Farmer	300	50	Mo
Barbara	32	F					N Carolina
Sylvanus	5	M					Mo
Margaret	3/12	F					"

Sylvanus's father has died, so he is temporarily surnamed DELLINGER and living with his step-father and remarried mother.  Listed three households from Sylvanus's uncle, Lawrence D. STROUP.

3.  1870 Census Every-Name-Index/Images (online at Ancestry.com, Image #12 of 13):  Greenville P.O., Cowen Twp., Wayne Co., MO, Roll M593_825, p. 190B, PN 12, 82/84, enumerated 8 Jun 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤•

Stroup William L	32	M	W	Farmer	1000	300	North Carolina
______ Margeret E	39	F	W	Keeping House			North Carolina
______ Sylvanus S	15	M	W	At Home			Missouri
______ Franklin S	17	M	W	At Home			Missouri

Sylvanus is completely orphaned now (his mother died and his step-father has remarried).  Despite the incorrect middle initial, this has to be Sylvanus's uncle, William Henry STROUP (Margaret is William's unmarried sister, not his wife).  I do not know where Franklin S. STROUP fits in.  Listed next to Sylvanus's uncle, Sydney A. STROUP. 

3.  1880 Census Every-Name-Index/Images (online at Ancestry.com, Image #12 of 13):  Fillmore Twp., Bollinger Co., MO, Roll T9_674 (Book 1), p. 530B, PN 17, SD 2, ED 192, enumerated 11 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	7	8	9	10	13	24	25	26
122	125	Stroup Stanhope	W	M	24				/	Farmer	MO	NC	NC
		______ Eliza	W	F	21		Wife		/	Keeping house	MO
		______ Mary E	W	F	3/12	Feb	Dau	/			MO	MO	MO

4.  1890 Census:  the 1890 Census Population Schedules were destroyed.

5.  1900 Census Every-Name-Index/Images (online at Ancestry.com, Image #19 of 25):  Cedar Creek Twp., Wayne Co., MO, Roll T623_907, p. 44A, SN 10, SD 12, ED 151, enumerated 21 Jun 1900, official enumeration date 1 Jun 1900 (extracted by Diana Gale Matthiesen):¤•

1900:  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

7

8

9

10

11

12

13

14

15

19

20

21

22

23

24

25

26

27

28

176

176

Stroup Hope S

Head

W

M

Dec 1855

44

M

23

MO

MO

MO

Farmer

6

Y

•

Y

O

F

F

123

______ Mary ?

Wife

W

F

Nov 1858

41

M

23

8

6

MO

MO

MO

Y

Y

Y

______ Ida E

Dau

W

F

Jan 1882

18

S

MO

MO

MO

6

Y

Y

Y

______ Birdie V

Dau

W

F

Sep 1884

15

S

MO

MO

MO

6

Y

Y

Y

______ Hattie J

Dau

W

F

Jul 1886

13

S

MO

MO

MO

6

Y

Y

Y

______ Monroe H

Son

W

M

Mar 1889

11

S

MO

MO

MO

Farm labor

6

Y

Y

Y

______ Rosa A

Dau

W

F

Sep 1891

8

S

MO

MO

MO

6

Y

•

Y

______ William L

Son

W

M

Nov 1892

7

S

MO

MO

MO

6

Y

Y

Y

Listed three households from Stanhope's first cousin, Henry D. P. STROUP.

6.  1910 Census Every-Name-Index/Images (online at Ancestry.com, Image #30 of 32):  Cedar Creek Twp., Wayne Co., MO, Roll T624_827 (Book 2), p. 179B, SN 15B, SD 11 ED 157, enumerated 9 May 1910, official enumeration date 15 Apr 1910 (extracted by Diana Gale Matthiesen):¤•

1910:  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

7

8

9

10

11

12

13

14

17

18

19

20

21

22

23

24

25

26

27

28

29

296

310

Stroup Stanhope S

Head

M

W

54

M1

37

MO

NC

NC

Eng

Farmer

General farm

Emp

N

0

Y

N

O

F

F

205

______ Mary E

Wife

F

W

53

M1

37

8

6

MO

KY

KY

Eng

None

Y

Y

______ Monroe H

Son

M

W

22

S

MO

MO

MO

Eng

Farm Laborer

working out

W

N

0

Y

Y

______ Rasa A

Dau

F

W

18

S

MO

MO

MO

Eng

None

Y

Y

Y

______ Wellie L A

Son

M

W

16

S

MO

MO

MO

Eng

Farm Laborer

Home farm

W

N

0

Y

Y

Y

7.  1920 Census Every-Name-Index/Images (online at Ancestry.com, Image #6 of 20):  Cascade & Gravelton, Cedar Creek Twp., Wayne Co., MO, Roll T625_963, p. 4A, SN 4A, SD 11, ED 174, enumerated 15 Jan 1920, official enumeration date 1 Jan 1920 (extracted by Diana Gale Matthiesen):¤•

1920:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

2

3

4

5

6

7

9

10

11

12

16

17

18

19

21

23

25

26

27

28

29

Fm

49

51

Spain Jasper

Head

R

M

W

52

M

Y

Y

MO

MO

MO

Y

Farmer

Gen farm

OA

40

"   Verda

Wife

F

W

35

M

Y

Y

MO

MO

MO

Y

None

[Jasper & Verda's children]

Strop Mary

M-in-law

F

W

63

W

Y

Y

MO

MO

MO

Y

None

8.  1930 Census Every-Name-Index/Images (online at Ancestry.com):  can't find.

9.  Dorris Cemetery [1.5 mi from Buckhorn], Madison Co., MO (online at the Madison County MOGenWeb site; transcribed and submitted by Jeanette Henson McClure):

Stroup, Stanhope	28 Dec 1855	07 Mar 1916
Stroup, Mary Eliza	20 Nov 1857	29 Sep 1937
Stroup, Mary E.	02 Mar 1880	10 Oct 1884	d/o S.S. & M.E.

10.  Bollinger County, Missouri, Death Records (online at the Bollinger County MOGenWeb site; submitted by Debi Bentley):-

Name:	Mary E. STROUP
Gender | Race | Age:	Female | White | 5y 8m
Date of Death:	10 Oct 1884 1am
Nationality | Birthplace:	USA | Fillmore Twp
Deathplace:	Fillmore Twp., Bollinger Co., MO
Cause of Death:	Typhoid Fever
Date and Place of Burieal:	11 Oct 1884 | Wayne Co., MO
Certification:	A. Keehn, MD | Castor, MO

11.  One World Tree (online at Ancestry.com).

12.  LDS.  Family Search: Internet Genealogy Service: Pedigree Resource File (index to CDs, online at FamilySearch.org).

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

14.  Messages posted to the Stroup Family Genealogy Forum (online at GenForum.com).