Susannah must have been very much younger than Peter to be the mother of Rachel.  Either that or Rachel is fibbing about her age.

— born in Spencer Twp., Medina Co., OH:
7.  Martin STROUP, b. 1836-38
8.  (Rev.) Philip B. STROUP, b. 1839/40
9.  Eliza STROUP, b. 1840/1

The children, as listed, do not jibe well with the early censuses.

1.  Marriage Record:

2.  1830 Census Index/Images (online at Ancestry.com, Image #7 of 14; extracted by Diana Gale Matthiesen):¤•

1830

PA

Greene Co.

Richhill Twp.

Roll M19_162

p. 396

Ln. 2

Samuel Stroup

220 002 - 020 010

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
2 males	4 or under	1825-1830	= Parker (b. 1828/9) = George (b. 182?)
2 males	5-9	1820-1825	= Jackson (b. 1822) = Silas (b. 1820)
2 males	30-39	1790-1800	= Samuel = ?
2 females	5-9	1820-1825	= Lucinda = ?
1 female	20-29	1800-1810	= Rachel

Rachel is surely fibbing about her age.  in the Listed next to Charles ALLUM, who is next to John ALLUM.

3.  1840 Census Index/Images (online at Ancestry.com; Image #1-2 of 8 — mis-indexed "Steoup"; extracted by Diana Gale Matthiesen):¤•

1840

OH

Medina Co.

Spencer Twp.

p. 15 | pp. 175B-176A

Ln. 3

Saml Stroup

223 101 - 011 001

0500000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
2 males	4 or under	1835-1840	= Philip (b. 1839/40) = Martin (b. 1836-38)
2 males	5-9	1830-1835	= ? = Oliver (b. 1830/1)
3 males	10-14	1825-1830	= Parker (b. 1828/9) = George (b. 182?) = ?
1 male	15-19	1820-1825	= Silas or Jackson
1 male	30-39	1800-1810	= Samuel
1 female	5-9	1830-1835	= ?
1 female	10-14	1825-1830	= Lucinda
1 female	30-39	1800-1810	= Rachel
5	persons employed in agriculture

Rachel continues to fib about her age, but now Samuel is in the wrong age class, too.

4a.  1850 Census Index/Images (online at Ancestry.com; Image #30 of 33):  Spencer Twp., Medina Co., OH, p. 437B, 1819/1825, enumerated 16 Sep 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

Jackson Stroup	27	M		Blacksmith	800	Penn
_______ Delilah	23	F				O
_______ Oliver	19	M		Blacksmith		Penn
_______ Rachel	40	F				Do
James M Jeffries	32	M		Farmer		NY

Either Rachel is fibbing about her age or Samuel had an earlier wife because, at 40, she would be too young to be Jackson's mother, much less Silas's.  Listed two households from son, Silas STROPE (æ 29).  Considering how scattered Rachel's children are, it appears Samuel did not leave her well off; otherwise, she would surely have kept her children with her. 

4b.  1850 Census Index/Images (online at Ancestry.com; Image #17 of 27):  Homer Twp., Medina Co., OH, p. 162A, 136/136, enumerated 27 Jul 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):¤•

John Miller	50	M		Farmer	1875	Penn
Polly	50	F				Do
Henry Berry	12	M				NY
Eliza Strope	9	F				O

5.  1860 Census Every-Name-Index/Images (online at Ancestry.com):  Rachel not found, at least not as Rachel STROUP.

6.  Anon.  1881.  History of Medina County and Ohio.  Baskin & Battey, Historical Publ., Chicago, IL (online at GenealogyLibrary.com).  On p. 824:

Chatham Township... JACKSON STROUP, farmer and blacksmith; P.O. Chatham Center; born March 9, 1822, in Rich Hill Township, Greene Co., Penn., son of Samuel and Rachel (Rush) Stroup.  Samuel was son of Thomas, of German descent, to whom were born John, George, Millie and Lavina.  The father of Rachel was Peter Rush, a native of Pennsylvania.  Jackson was a lad of 13 when his parents came West.  His father located first in Spencer, purchasing land, for which he paid $5 per acre.  He did not remain long on this place, but moved about considerably before he died, renting land in different localities.  His death occurred in the year 1840.  His family consisted of nine children, all of whom lived to maturity.  They were Lucinda, Eliza, Jackson, Silas, George, Parker, Oliver, Martin, and Philip.  After the death of his father, Jackson took charge of the family, and kept them together, and maintained them until they were enabled to care for themselves...

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