1.  Census Index:  U.S. Selected Counties, 1820 (Broderbund CD-314):  not found.

2.  Census Index:  U.S. Selected Counties, 1830 (Broderbund CD-315):

1830

Sampson, Thomas

PA

Washington Co.

East Finly Twp

p. 326

He is the only Thomas SAMPSON in the county.

3.  Census Index:  U.S. Selected Counties, 1840 (Broderbund CD-316):

1840

Sampson, Thomas

PA

Washington Co.

E Findley Twp

p. 171

He is the only Thomas SAMPSON in the county.

4.  1850 Census Index/Microfilm (online at GenealogyLibrary.com):  East Finley Twp., Washington Co., PA, p. 540, 58/58, enumerated 24 Oct 1850 (extracted by Diana Gale Matthiesen):

Thomas Sampson	45	M	Farmer	1000	Md
Catharine "	40	F			Pa
William   "	21	M	"		"
Isaac     "	20	M	"		"
David     "	18	M	"		"

It's odd that they have no younger children.

5.  Broderbund.  World Family Trees.  Vol. 9, Pedigree No. 2824.