He married Mary Emaline Diamond on May 24, 1903, in McDonough County.

Mary was the daughter of John James Diamond and Mary Emma Potter.  She was born at Tennessee, McDonough County, Illinois, March 28, 1888.

Thomas and Mary became the parents of two daughters, but neither survived to adulthood.
 
 

From the files of Ina White Westfall, shared by Mary Jane White unknown original news source, verbatim transcription Thomas N. 'Sandy' Callihan, a "Q" switchman for several years and since 1926 an employe of the city of Galesburg, in the street department, died of a sudden heart attack at 2:30 o'clock Sunday afternoon in his home, 164 Lincoln street. He had been slightly ill for the past few days, and active until he was fatally stricken. Thomas Noble Callihan was born near Fountain Green on Nov. 16, 1883, the son of S. A. and Margaret Callihan.  The family moved to Tennessee, Ill., when he was a youth of five.  He attended schools there, and in that town married Mary Diamond on May 24, 1903.  To this union two daughters were born, one of whom died in infancy, while the other, Geraldine, succumbed on May 12, at the age of 13. The Callihans came to Galesburg in 1906, and he opened the first restaurant at the C.B. and Q. "humps."  He later entered the Burlington employe as a switchman.  He was forced to give up this work when he was hurt, and for the past 13 years worked on the street department. Mr. Callihan was widely known in the city, and was a devoted husband who loved his home life.  He was a member of the Mystic Workers. Surviving are his wife and four sisters, Mrs. Maude Bowles, Mrs. Lutie Ewalt and Mrs. Clo Thomas of Galesburg, and Mrs. Jewel Black of San Bernardino, Calif.  There are several nieces and nephews remaining.  His parents and a brother, Ed, preceded him in death. Funeral services will be held at 2:30 o'clock Tuesday afternoon from the Baptist church. Friends may call at the home, 164 Lincoln street, this evening and Tuesday morning.

The daughters of Thomas N. Callihan and Mary E. Diamond were:

i.	Geraldine Maud Callihan, born December 12, 1904, in Tennessee, McDonough County, died May 12, 1918, at Galesburg.  Burial at Linwood Cemetery, Galesburg.
ii.	Dorothea Anita Callihan, born December 24, 1906, died January 25, 1907.  Burial at Majorville Cemetery, Hancock County.

Callihan, Thomas, head, white, male, Mar 18?7 [illegible], 53, married for 32 years, born IL, both parents born PA, restaurant, months not employed - 0, could read, write and speak English, owned his home

Margaret, wife, white, female, July 1851, 49, married for 32 years; mother of 7 children, 6 living; born IL, father born SC, mother born NC, could read, write and speak English

Lutie E, daughter, white, female, Apr 1881, 19, single, born IL, both parents born IL, clerk restr, months not employed - 0, could read, write and speak English

Thomas Jr N, son, white, male, Nov 1883, 16, single, born IL, both parents born IL, teamster, months not employed - 4, could read, write and speak English

Jewel K, daughter, white, female, Jun 1887, 12, single, born IL, both parents born IL, telephone girl, months not employed - 0, could read, write and speak English

Clo B, daughter, white, female, Mar 1893, 7, single, born IL, both parents born IL, at school, attended school for 8 months, could read, write and speak English

Potter, William, head, white, male, Jan 1841, 59, married for 33 years, born unknown, both parents born unknown, farmer, months not employed - 4, could read but not write, spoke English, owned his home free of mortgage

Harriett, wife, white, female, Nov 1850, 49, married for 33 years; mother of 7 children, 5 living; born IL, father born OH, mother born IN, could not read or write, spoke English

Leonard, son, white, male, May 1868, 32, single, born IL, father born unknown, mother born IL, miner clay, months not employed - 3, could read but not write, spoke English

Janie, daughter, white, female, Jan 1882, 18, single, born IL, father born unknown, mother born IL, school attendance - 0 months, could read, write and speak English

Pearl, daughter, white, female, Jan 1884, 16, single, born IL, father born unknown, mother born IL, school attendance - 0 months, could read, write and speak English

Diamond, Mary, granddaughter, white, female, Mar 1888, 12, single, born IL, both parents born IL, at school for 8 months, could read, write and speak English

Callihan, Sandy, head, male, white, 26, married (1st) for 7 years, born IL, both parents born IL, spoke English, cook, lunch room, employee, whether out of work on April 15, 1910 - no, number of weeks out of work during 1909 - 0, could read and write, rented his home

Mary, wife, female, white, 23, married (1st) for 7 years; mother of 2 children, 1 living; born IL, both parents born IL

Jeraldine, daughter, female, white, 5, single, born IL, both parents born IL

Callahan, Thomas S, head, renter, male, white, 36, married, could read and write, born IL, both parents born IL, spoke English, switchman, CB&Q, working for wages

Mary E, wife, male [sic], white, 30, married, could read and write, born IL, both parents born IL, spoke English

Callihan, Thomas M, head, owned his home, home value 4500, owned a radio, male, white, 45, married, age at first marriage - 19, could read and write, born IL, both parents born IL, laborer, city; whether a veteran of the U. S. military or naval forces mobilized for any war or expedition - no

Mary E, wife, female, white, 40, married, age at first marriage - 19, could read and write, born IL, both parents born IL, spoke English