Table:
0
A
B
C
D
E
1
District
Vacator
Reason for change
Successor
Date successor seated
2
Colorado At-large
James B. Belford (R)
Lost contested election December 13, 1877
Thomas M. Patterson (D)
December 13, 1877
3
California 4th
Romualdo Pacheco (R)
Lost contested election February 7, 1878
Peter D. Wigginton (D)
February 7, 1878
4
Louisiana 3rd
Chester B. Darrall (R)
Lost contested election February 20, 1878
Joseph H. Acklen (D)
February 20, 1878
5
Louisiana 5th
John E. Leonard (R)
Died March 15, 1878
J. Smith Young (D)
November 5, 1878
6
Massachusetts 3rd
Walbridge A. Field (R)
Lost contested election March 28, 1878
Benjamin Dean (D)
March 28, 1878
7
New York 16th
Terence J. Quinn (D)
Died June 18, 1878
John M. Bailey (R)
November 5, 1878
8
Nebraska At-large
Frank Welch (R)
Died September 4, 1878
Thomas J. Majors (R)
November 5, 1878
9
Michigan 1st
Alpheus S. Williams (D)
Died December 21, 1878
Vacant
Not filled this term
10
Virginia 1st
Beverly B. Douglas (D)
Died December 22, 1878
Richard L. T. Beale (D)
January 23, 1879
11
Georgia 1st
Julian Hartridge (D)
Died January 8, 1879
William B. Fleming (D)
February 10, 1879
12
Texas 6th
Gustav Schleicher (D)
Died January 10, 1879
Vacant
Not filled this term

Questions and formulas:
Question: What district was the successor seated in March 28, 1878?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,E1="March 28, 1878"),1))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E12,E2:E12="March 28, 1878"),1))
Level: medium
Question: Who was the vacator for the district of Nebraska at-large?
Formula: UNIQUE(CHOOSECOLS(FILTER(A1:E1,A1="Nebraska At-large"),2))
Formula2: UNIQUE(CHOOSECOLS(FILTER(A2:E12,A2:A12="Nebraska At-large"),2))
Level: medium