Given the age difference between George and Sarah, one would assume he had a prior wife, yet there's no sign of any earlier children of his in the 1840 census.  Then again, his earlier children could be living with his late wife's family, so there is still the possibility that he had an earlier wife.

1.  Anon.  1966.  Marriage Index:  Ohio, 1789-1850.  Liahona Research, Orem, UT (Broderbund CD-400):

Bricker, Michael	Grace, Sarah	10 May 1827	Columbiana Co.
Stroup, George	Bricker, Sarah	20 Apr 1837	Columbiana Co.

2.  1840 Census Index/Images (online at Ancestry.com, Image #5-6 of 24; extracted by Diana Gale Matthiesen):¤•

1840

OH

Columbiana Co.

Knox Twp.

pp. 16A-16B

Ln. 8

George Stroup

201 000 100 - 000 001

0100000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
2 males	4 or under	1835-1840	= Aaron (b. 1839/40) = Eli (b. 1838)
1 male	10-14	1825-1830	= Hirum BRICKER (b. 1827/8)
1 male	40-49	1790-1800	= George (b. 1790)
1 female	30-39	1800-1810	= Sarah (b. 1807)
1	person employed in agriculture

3.  1850 Census Index/Images (online at Ancestry.com; Image #569 of 822):  District No. 24, Knox Twp., Columbiana Co., OH, p. 287A, 200/200, enumerated 6 Aug 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

Sarah Stroup	43	F		Farmer	1800	Ohio
Hirum Brichner	22	M		Farmer		Ohio
Eli Stroup	12	M				Ohio
Aaron Stroup	10	M				Ohio
Joseph Stroup	4	M				Ohio

Hirum is Sarah's son by a prior marriage.

4.  1860 Census Index/Images (online at Genealogy.com, Image #21 of 54):  Sandy P.O., Knox Twp., Columbiana Co., OH, Roll 948 (Book 1), p. 11A, PN 21, 170/158, enumerated 27 Jun 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):¤•

Sarah G. Stroup	53	M		Farmer	4000	505	Ohio
Hiram Bricker	32	F		"	1800	150	"
Eli Stroup	22	M		"			"
Aaron  "	20	M		"			"

Hirum is Sarah's son by a prior marriage.

5.  1870 Census Index/Images (online at Genealogy.com, Image #47 of 54):  Alliance? P.O., Knox Twp., Columbiana Co., OH, Roll 1183 (Book 1), p. 173A, PN 47, 370/370, enumerated 28 Jul 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):¤•

Stroup Sarah	63	F	W	Keeping House			O
______ Aaron	30	M	W	Farmer	3500	600	O

6.  1880 Census (indexed at FamilySearch.org; page image online at Ancestry.com, Image #24 of 49):  Knox Twp., Columbiana Co., OH, Roll T9-1002, p. 409D, PN 24, SD 8, ED 50, enumerated 12 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	11	13	24	25	26
216	219	Stroup Aaron	W	M	40		/		Farmer	O	O	O
		______ Sarah	W	F	73	Mother		/	Keeping House	O	Md	Md

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

8.  Email from Karen Cockerell (10/05).