1.  Marriage Record:

2.  1870 Census Every-Name-Index/Images (online at Ancestry.com):  can't find Alexander or his brother, Adam, and Adam, at least, is married at this point.  Based on the 1880 Census, they ought to be in Colorado or Idaho Territory or possibly New Mexico.  There was no 1870 NM census, so maybe that's where they were.

3.  1880 Census Every-Name-Index/Images (online at Ancestry.com, Image #29 of 53):  Island City Pct., Union Co., OR, Roll T9_1084, pp. 133D-134A, PN 26-27, SD 110, ED 116, enumerated 18-19 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

10

11

13

15

18

24

25

26

208

219

Culp Adam

W

M

35

/

Farmer

Vir

Penna

Penna

____ Ellen

W

F

23

Wife

/

Keeps house

Iowa

Ohio

Ohio

____ Ruth

W

F

15

Daughter

/

At home

Kansas

Vir

Ind

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____ Catherine

W

F

13

"

/

Colorado

Vir

Iowa

____ Mary

W

F

10

"

/

"

"

"

____ Barbra

W

F

8

"

/

/

New Mexico

"

"

____ John

W

M

73

Father

/

Feable

Penna

Penna

Penna

____ Catherine

W

F

62

Mother

/

Assists in Home w

"

"

"

____ Alexander

W

M

30

Brother

/

Teamster

Vir

"

"

____ Ellen J

W

F

4

Niece

/

Idaho Ter

Vir

____ Olive L

W

F

3

"

/

"

"

____ Matilda

W

F

2

"

/

"

"