1.  1850 Census Index/Microfilm (online at GenealogyLibrary.com):  Upper Towamensing Twp., Carbon Co., PA, p. 394A, 23/23, enumerated 18 Sep 1850 (extracted by Diana Gale Matthiesen):

Charles Belford	38	M		farmer	600	Pa
Anne	39	F				"
[Charles & Anna's children and Charles's mother]
Selinda Stroup	24	F				"

Anna (STRAUB) BELFORD is Salinda's sister. 

2.  Index and Transcription of the 1860 Census of Carbon County, Pennsylvania (online at the USGenWeb Census Project):  cannot find our subject.

3.  1870 Census Images (online at Ancestry.com; Image #39 of 48):  Parryville P.O., Franklin Twp., Carbon Co., PA, p. 82A, PN 39, 261/282, enumerated 13 Jul 1870 (extracted by Diana Gale Matthiesen):

Belford Charles	58	M	W	Farmer	6000	1000	Pennsylvania
_______ Anna	58	F	W	Keeping house			"
[Charles & Anna's child, et al.]
Straub Salinda	43	F	W	House Keeper			"

Anna (STRAUB) BELFORD is Salinda's sister. 

4.  1880 United States Census and National Index (LDS Family History Resource File: CD-ROM Library):

Census Place: Parryville, Carbon, Pennsylvania
Source: FHL Film 1255108; NARA Film T9-1108; Pg 516C
	Relation	Sex	Marr	Race	Age	Birthplace	Occupation	Fa	Mo
Charles BELLFORT	Self	M	M	W	67	PA	Farmer	PA	PA
Anna BELLFORT	Wife	F	M	W	67	PA	Keeping House	PA	PA
Charles BELLFORT	GSon	M	S	W	15	PA	Farmer	PA	NJ
Salinda STRAUP	SisterL	F	S	W	53	PA	Servant	PA	PA