David Johnson Rex was born near Richmond, Jefferson County, Ohio at the Rex farm on 7 Jan 1851. He was the second of seven children born to John Styles and Rachel Scott Rex. David Rex grew up and worked on the Rex farm and learned the discipline of farm life. David J. Rex was part of the second graduating class of Wooster College, Wooster, Ohio in 1871.

In 1872 David Rex, in order to begin a business of his own, left Ohio and settled in the industrial town Pittsburgh, Pennsylvania that was about 30 miles from his home. While in western Pennsylvania, he met and married Harriet Elizabeth Reed, daughter of Samuel Miller Reed, Jr. and Eleanor Ferguson of New Alexandria, Westmoreland County, Pennsylvania

In 1873 he founded D. J. Rex & Co., Iron City Steam Paper Box Factory at 967 Liberty Street in Pittsburgh, PA. The factory had five floors covering 10,000 square feet, and with the use of steam-working machinery, he was able to create a vast array of paper boxes, including tea caddies, cigar boxes, and hatboxes.

In November 1881 David Rex, his wife, and the two children he had at the time, moved to an area of Chartiers Township, east of Pittsburgh, which had several years earlier been opened for settlement by Thomas Ingram.

In the 1890's several residents of this area, including David Rex, decided to try to incorporate Ingram as a borough. A petition was submitted to the court to make Ingram a borough, but was defeated . Two years later, in June 1902, a committee was again appointed to make the formal petition to the Allegheny County Court. This time almost 85 per cent of the property owners placed their names on the petition. Ingram became incorporated as a borough on August 2, 1902. The first burgess elected for the new borough was David Johnson Rex. David Rex lived in the community for 65 years where he was respected as a civic leader, a pillar of his church, and a business leader.

In 1914 David Rex entered the retail lumber business in the neighboring town of Crafton. The business was named the Crafton Lumber Company. He also became a director of the First National Bank of Crafton and served in a similar capacity with the Crafton National Bank into the 1940's. Mr. Rex also owned extensive real estate including several apartment buildings and homes, which he rented out, as well as the Rex Building in downtown Ingram.

In the early days of his residence in Ingram, David Rex was an active member of the First Presbyterian Church of Crafton and sang in the choir there. On 7 October 1892, he transferred his membership to the Ingram Presbyterian Church where he took personal charge of the Christmas Cantatas.

He enjoyed included gardening, pitching quoits and playing euchre. He had also been a passionate croquet player since the age of 15.

David Rex was also known as a family man. He and his wife had nine children and over 45 grand children and great grandchildren. All but two of his children married and most of them stayed in Ingram or in nearby communities to raise their families.
 

The children of David and Harriet Rex were:

1. John Scott Rex was born 03 October 1877 in Allegheny City, PA. He married Nellie T. Rhodes 14 June 1899 in Pittsburgh, PA,, daughter of S.T. Rhodes. She was born 09 August 1877 in Stroudsburg, Monroe Co., PA.
The children of John and Nellie Rex were David Ford Rex, Helen Thompson Rex, Nellie Rex, John Rex, Harriet E. Rex, and John Stuart Rex

2. Eleanor Reed Rex who was born 27 November 1879 and died August 1974 in Ingram, PA.

3. Frank Clyde Rex was born 03 August 1882 in Ingram, Allegheny Co., PA and died September 1967 in Allegheny Co., PA. He married Florence Anna McNary 25 October 1906 in Pittsburgh, PA. She was born 07 March 1885 in Hickory, Washington Co., PA and died 1961 in Allegheny Co., PA.

4. Edward Geary Rex was born 09 July 1884 in Ingram, Allegheny Co, PA and died 21 December 1956 in Pennsylvania. He married Margaret V. Harper 12 November 1908 in Venice, Washington Co., PA, daughter of John W. Harper. She was born 02 September 1885 in Venice, Washington Co., PA1, and died 09 January 1973 in New Castle, Lawrence Co., PA.

5. Rachel Mary Rex was born 23 January 1886 in Ingram, Allegheny Co., PA, and died May 1974 in California. She married Guy Neely Rumbaugh 14 June 1911 in Ingram, Allegheny Co., PA, son of John and Anna Rumbaugh. He was born 19 October 1881 in Bradford, McKean Co., PA.

6. Samuel Miller Rex was born 22 October 1888 in Ingram, Allegheny Co, PA, and died 19 February 1972 in Greentree, Allegheny Co., PA. He married Mary Elizabeth McNary 27 June 1914 in Pittsburgh, PA, daughter of Edward McNary and Jane Campbell. She was born 07 July 1889 in Hickory, Washington Co., PA, and died 16 July 1972 in Greentree, Allegheny Co., PA.

7. Harriet Elizabeth Rex was born 09 January 1891 in Ingram, Allegheny Co., PA, and died 18 September 1981 in New Castle, Lawrence Co., PA. She married William F. Aull 04 September 1912 in Ingram, Allegheny Co, PA273, son of Francis Aull and Isabel Irwin. He was born 17 July 1889 in Pittsburgh, Allegheny Co., PA, and died 11 January 1965 in Pittsburgh, Allegheny Co., PA.

8. Laura Margaret Rex was born 20 March 1892 in Ingram, Allegheny Co., PA and died in 1959 in Ingram, PA

9. David Johnson Rex II was born 03 September 1894 in Ingram, Allegheny Co., PA and died 26 August 1977 in Ingram, Allegheny Co., PA. He married Hazel Josephine Reno 25 September 1919 in Pittsburgh, Allegheny Co., PA, daughter of Isaac Reno and Carrie Albertsmaier. She was born 29 September 1894 in Pittsburgh, Allegheny Co.,PA, and died 1966 in Allegheny Co., PA.

David Johnson Rex, Sr. died in his home at 24 Mainsgate, Ingram, PA on the 6th September 1946 at 10:15 PM.. His wife had preceded him in death in 1924 and David Rex was buried in a grave beside hers in Chartiers Cemetery, Carnegie, PA.