1a.  Liahona Research (Orem, UT), compilers.  1996. Marriage Index:  Ohio, 1789-1850 (Broderbund CD-400):  not found.

1b.  LDS.  Family Search: Internet Genealogy Service: International Genealogical Index (IGI).  Multiple entries.

John WILLIAMSON Spouse: Rosanna/Rossanah ELY Marriage: ca. 1810/1811/1836, Delaware, Ohio Sources: patron submissions

2.  Census Index:  U.S. Selected Counties, 1810 (Broderbund CD-313):  the 1810 Ohio census was lost (except for Washington Co.).

3.  Family Quest Archives:  Ohio Federal Census 1820:  Clark, Coshocton, Gallia, Hocking, Huron, Knox, Lawrence, Meigs, and Monroe Counties.  Heritage Quest CD M33-88 (extracted by Diana Gale Matthiesen).

1820

OH

Knox Co.

Sunbery Twp.

p. 110

John Williams

300010-30100-0-001

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
3 males	9 or under	1810-1820	= William (b. 1814) = Peter (b. 1813) = Sylvester (b. 1812)
1 male	26-44	1775-1794	= John (b. 1783)
3 females	9 or under	1810-1820	= Christina (b. 1819) = Eliza (b. 1817) = Lucinda (b. 1816)
1 female	16-25	1794-1804	= Rosanna (b. 1792/3)
1	person engaged in manufacturing

Living two doors down from Rosanna's father, Michael ELY. 

4.  1830 Census Index and Digital Images (online at Ancestry.com; Image #5 of 8; extracted by Diana Gale Matthiesen):

1830

OH

Delaware Co.

Sunbury Twp.

p. 109

Ln. 16

John Williamson

400 300 100 010 - 012 000 100

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
4 males	4 or under	1825-1830	= ? = John (b. 1828) = Michael (b. 1826) = James (b. 1824)
3 males	15-19	1810-1815	= William (b. 1814) = Peter (b. 1813) = Sylvester (b. 1812)
1 male	40-49	1780-1790	= John (b. 1783)
1 male	80-89	1740-1750	= father? father-in-law?
1 female	5-9	1820-1825	= Christina (b. 1819)
2 females	10-14	1815-1820	= Eliza (b. 1817) = Lucinda (b. 1816)
1 female	40-49	1780-1790	= Rosanna (b. 1792/3)

5.  1840 Census Index and Digital Images (online at Ancestry.com; Image #5-6 of 14; extracted by Diana Gale Matthiesen):

1840

OH

Delaware Co.

Trenton Twp.

pp. 148B-149A

Ln. 4

John Williamson

022 100 010 - 100 020 100

0300000

These data indicate:

No. & Sex	Age Class	Therefore Born	Individuals Inferred
2 males	5-9	1830-1835	= Solomon (b. 1832) = Henry (b. 1830)
2 males	10-14	1825-1830	= John (b. 1828) = Michael (b. 1826)
1 male	15-19	1820-1825	= James (b. 1824)
1 male	50-59	1780-1790	= John (b. 1783)
1 female	4 or under	1835-1840	= Mary Jane (b. 1836)
2 females	20-29	1810-1820	= Eliza (b. 1817) = Lucinda (b. 1816)
1 female	40-49	1790-1800	= Rosanna (b. 1792/3)
3	persons employed in agriculture

Listed one line from their son, Peter WILLIAMSON (00001-00001), an apparent newlywed.

6.  1850 Census Index/Images (online at Ancestry.com; Image #29 of 30):  Trenton Twp., Delaware Co., OH, p. 160B, 927/928, enumerated 27 Jul 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

John Williamson	67	M		Farmer		Pa
Rosanna   "	57	F				Pa
John      "  Jr	20	M		Farmer		O
Henry     "	19	M		Farmer		O
Solomon   "	17	M		Farmer		O
Mary Jane "	13	F				O

Listed two households from their son, Michael WILLIAMSON (æ 23, b. OH, wife Loisa A.).

7.  1860 Census Images (online at Ancestry.com; Image #17 of 26):  Vans Valley P.O., Trenton Twp., Delaware Co., OH, p. 91B, PN 50, 371/376, enumerated 15 Jun 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

John Williamson	77	M		Farmer		3000	Pa
Rosanna	67	F					"

Listed next to son, "Matson" WILLIAMSON (æ 48, b. OH, wife Mary), who is next to "Matson" WILLIAMSON (æ 22, b. OH, wife Emily).

8.  Family Quest Archives:  Ohio 1870 Census Index.  Heritage Quest ACD-0014:  not found, as expected.

9.  Anon.  1880.  History of Delaware [County] and Ohio.  O.L. Baskin, Chicago (online at Heritage Pursuit):

p. 180	CHAPTER II... SETTLEMENT OF THE COUNTY BY THE WHITES...
p. 194	In the same year as given above (1807), settlements were made in Trenton Township... John Culver, Michael Ely and their families were the first settlers north of Culver's Creek, and located in the settlement in 1809.  Shortly after them John Williamson came and bought land of Ely, and during the year married his daughter Rosanna...
p. 587	CHAPTER XXVII. TRENTON TOWNSHIP... MANY of our elderly readers will readily remember the time when a large portion of the east half of the county was known as Sunbury Township.  It was the third township created after the organization of the county and dates back to June 16, 1808... it was whittled off... to what is now Trenton Township...
p. 589	The first settlement made north of Culver's Creek was by John Culver and Michael Ely.  They are noticed among the arrivals of 1809.  Not long after them came John Williamson and bought land from Ely.  He was a bachelor when he came to the settlement, but, sometime during the year 1810, he married Ely's daughter, Rosanna.  Their son, Madison Williamson, is reported as the first birth in the township...
p. 590	But few of the early settlers of the township are still living.  Most of them lie sleeping in the little graveyards. The first birth which occurred was that of Madison Williamson, who was born about the commencement of the war of 1812.  He was a son of John Williamson, an emigrant of 1809, who, in 1810, was married to a Miss Ely, and was the first marriage, probably, to take place in the community.

10.  The Raymond Martin Bell Anthology.   "The Families of George Ealy, East Finley Township, and Michael Ely, Buffalo Township, Washington [County], Pennsylvania" (online at the Washington County PAGenWeb site).

11.  Messages in the Ely Family Genealogy Forum (online at GenForum.com).