Amelia is surnamed WATT in the 1850 census and STRAUB in the 1860 census, so clearly she is George's adopted daughter.  She may have been Susanna's daughter from a prior marriage to a Mr. WATT.

— born in Snyder Co., PA:
  5.  Daniel Samuel STRAUB, b. 14 Jul 1856 

— born in Sugar Valley, Clinton Co., PA
  6.  Barbara STRAUB, b. 27 Oct 1858
  7.  John STRAUB, b. 14 Dec 1860
  8.  George P. STRAUB, b. 20 Feb 1863
  9.  Harrison STRAUB, b. 13 Jun 1866

— born in Georgetown, Carroll Co., IL:
10.  Clara STRAUB, b. 1868/9; d. 22 Jun 1879 (æ 9y 8m 15d)

1.  Marriage Record:

2.  1850 Census Index/Images (online at Ancestry.com; Image #18 of 33):  Perry [now West Perry] Twp., Union [now Snyder] Co., PA, p. 106B, 124/124, enumerated 18 Nov 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

George Straub	30	M	Labourer	1000	Penna
Susanah Straub	23	F			"
William Straub	7	M			"
Amelia Watt	4	F			"
Emanuel Straub	1	M			"
Hanah Straub	14	F			"
John A. Heiser	16	M			"
Barbara Hiser	48	F			"

William is George's son from his prior marriage to Mary SNYDER.  Amelia WATT later becomes George's adopted daughter (see 1860); she may be (likely is) Susanna's child from a prior marriage.  Emanuel is their first child together.  Hannah may be George's niece.  Barbara is almost certainly Susanna's mother; John is almost certainly Susannah's youngest brother.  They are listed next to John H. STRAUB, two households from John K. SNYDER, five households from John TRAUB, and 17 households from George's parents, Daniel S. & Elizabeth (HAHN) STRAUB. 

3.  1860 Census Index/Images (online at Genealogy.com, Image #1-2 of 32):  Mill Hall P.O., Green Twp., Clinton Co., PA, Roll 1097 (Book 1), pp. 133-134, PN 140-141, 984/988, enumerated 26 Jun 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):¤•

George Stroup	40	M		Farmer		500	Penna
Susan      "	33	F					"
William    "	18	M					"
Amelia     "	14	F					"
Christian  "	8	M					"
Samuel     "	3	M					"
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Barbara Stroup	1	F					Penna

4.  1870 Census Index/Images (online at Genealogy.com; Image #17 of 22):  Mount Carroll P.O., Salem Twp., Carroll Co., IL, p. 215AB, 133/133, enumerated 25 Jul 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤•

Stroup George	51	M	W	Farmer	400	300	Pennsylvania
______ Susan	43	F	W				Pennsylvania
______ Christian	18	M	W				Pennsylvania
______ Daniel	13	M	W				Pennsylvania
[next page]
Stroup Barbara	11	F	W				Pennsylvania
______ John	9	M	W				Pennsylvania
______ George	6	M	W				Pennsylvania
______ Harrison	4	M	W				Pennsylvania
______ Clara	1	F	W				Illinois

5.  1880 Census (indexed at FamilySearch.org; page image online at Ancestry.com, Image #6 of 24):  Fair Haven Twp., Carroll Co., IL, Roll 178 (Book 1), p. 488B, PN 6, SD 2, ED 13, enumerated 5/7 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

18

21

22

23

24

25

26

56

57

Straub George

W

M

59

Father

/

Farmer

Penn

Penn

Penn

______ Susan

W

F

52

Mother

/

Keeping House

Penn

Penn

Penn

______ Christian

W

M

26

Son

/

Farmer

/

/

Penn

Penn

Penn

______ John

W

M

18

Son

/

Farm Laborer

Penn

Penn

Penn

______ George

W

M

17

Son

/

without Occupation

Penn

Penn

Penn

______ Harrison

W

M

14

Son

/

Farm Laborer

/

/

/

/

Penn

Penn

Penn

Hiller Louise

W

F

20

Servant

/

Hired? Girl

Penn

Elsass

Elsass

6.  1890 Census:  the 1890 Census Population Schedules were destroyed.

7.  1900 Census Index/Images (online at Genealogy.com, Image #12 of 29):  Fair Haven Twp., Carroll Co., IL, Roll 239 (Book 2), p. 122A, SN 7, SD 3, ED 14, enumerated 1 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

22

23

24

25

26

27

28

128

130

Straub George

Head

W

M

Dec 1820

79

M

54

PA

PA

PA

Farmer

Y

Y

Y

O

F

F

4

______ Susana

Wife

W

F

Mar 1827

73

M

54

12

7

PA

PA

PA

Y

Y

Y

______ John

Son

W

M

Dec 1860

39

S

PA

PA

PA

Carpenter

Y

Y

Y

______ George

Son

W

M

Feb 1863

37

S

PA

PA

PA

farm laborer

Y

Y

Y

______ Harrison

Son

W

M

Jun 1866

33

S

PA

PA

PA

farm laborer

Y

Y

Y

8.  1900 Census Every-Name-Index/Images (online at Ancestry.com, Image #12 of 29):  Fair Haven Twp., Carroll Co., IL, Roll T623_239, p. 122A, SN 7, SD 3, ED 14, enumerated 1 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

22

23

24

25

26

27

28

128

130

Straub George

Head

W

M

Dec 1820

79

M

54

PA

PA

PA

farmer

Y

Y

Y

O

F

F

4

______ Susana

Wife

W

F

Mar 1827

73

M

54

12

7

PA

PA

PA

Keeping House

Y

Y

Y

______ John

Son

W

M

Dec 1860

39

S

PA

PA

PA

Carpenter

Y

Y

Y

______ George

Son

W

M

Feb 1863

37

S

PA

PA

PA

farm laborer

Y

Y

Y

______ Harrison

Son

W

M

Jun 1866

33

S

PA

PA

PA

farm laborer

Y

Y

Y

9.  1910 Census Index/Images (online at Ancestry.com, Image #15 of 28):  Fair Haven Twp., Carroll Co., IL, Roll T624_232 (Part 2), p. 25A, SN 8A, SD 4, ED 3, enumerated 5/6 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

12

13

14

17

18

19

20

21

22

23

24

26

27

28

29

168

169

Straub George Sr

Head

M

W

89

Wd

PA

PA

PA

Eng

Farmer

N

N

O

M

F

150

______ John

Son

M

W

49

S

PA

PA

PA

Eng

None

Y

Y

______ George P

Son

M

W

47

S

PA

PA

PA

Eng

Labour

Odd Jobs

W

N

0

Y

Y

______ Harrison

Son

M

W

43

S

PA

PA

PA

Eng

Farm Laborer

Horse Farm

W

Y

Y

10.  "Carroll County Biographies:  Jacob Straub."  A Goodly Heritage.  Supplement #1, Spring 1975 (online at the Carroll County "Genealogy Trails" web site):

George Straub (1820-1913) was employed as a logger in Penna.  He came to Illinois in the spring of 1867 and first settled near Georgetown.  Later he removed to Fair Haven Township, and settled on a farm one mile east of Chadwick.  At the time of his death he was the oldest citizen in that township.  Mr. Straub was twice married.  His first wife, Mary (Snyder) Straub, bore several children.  Only two survived infancy: William H., who came with his father to Carroll County, resided near Manchester, Iowa; and Amelia was the wife of John H. Forry of Rock Creek Twp.  His second wife, Susanna (Heiser) Straub, preceded him in death in 1904 after 55 years of marriage.  She bore him seven children: Christian, who served as custodian of the Chadwick Public Schools for 33 years; Daniel, who left Carroll County in 1880 to settle in Nebraska; Barbara, wife of John Crockett Moore of Freeport; John, who farmed and worked at carpentry in Chadwick; George and Harrion (sic), who farmed the family homestead one mile east of Chadwick; and Clara, who died at nine years of age.

Amelia is surnamed WATT in the 1850 census, so she was not Mary (SNYDER) STRAUB's daughter.  She was likely the daughter of George's second wife from a prior marriage of hers.

11.  Edward Adlum Straub.  1909.  Life and Civil War Services of Edward A. Straub … Written by Himself.  Press of J.H. Yewdale & Sons, Milwaukee, WI (excerpts online at the Carroll County sections of the Illinois Trails web site).  Mentions that our subject's first wife was Mary SNYDER.  (Edward Adlum STRAUB is our subject's nephew.)