Catherine Riley was born on 16 November 1880 at the Riley ranch/farm. In census records, she is called Kate, Katie, and Katherine; however, her tombstone and her death certificate record her official name as Catherine. According to the Heirship Affidavit, she never got married and died without a will on 29 June 1956 at the age of 75.

In the 1900 census, she was 20 years old and living with the rest of her family at the Riley Ranch/Farm. At 30 years old, the 1910 census has her living with her parents and 4 of her siblings. By 1920, her father had passed away and it appears that her mother, Margaret Ellen, still lived at the Riley Ranch with part of her family; Margaret Ellen had her mother (Catherine McNamara), her brother (George McNamara who also never married), and "Katherine" Riley all living there as part of the family.

By 1930, the Great Depression had hit, and it appears that the family members are still living at the Riley Ranch. In the 1930 census, the family members now include Margaret Ellen, Katherine, James Egan, and George McNamara (Note: Catherine McNamara had died in 1921). As noted in the story of William Joseph Riley, the family was having some difficult times due to the Depression, as was the rest of the nation. It is noteworthy that James Egan was living with the remaining family at this time. James appeared to help support the family and to be a key figure in handling the land with oil and gas leases that was part of the family income. Catherine Riley's mother died in 1942, and it is felt that Catherine came to depend on her brother James.

Catherine owned part of the land that was the heritage from John Joseph Riley that was partitioned to family members in 1929 (266 acres) and then part of the land partitioned to family members after the death of Margaret Ellen Riley. Catherine died in San Antonio in 1956 at age 75. Her death certificate says that she had lived there for two years and that she owned her own home. The certificate also says that her home was a source of business; so she probably had boarders or a boarding house.

She is buried in the Runge Catholic Cemetery in the same area as other members of her family.