David P. Ruby was born in Susquehanna, Cambria, Pennsylvania in 1919. He was born to Elsie and Freman Ruby and was a younger sibling to Norman Eldon Ruby, Elizabeth (Ruby) Wager, and George T. Ruby but also the older sibling to Helen (Ruby) Michaels and Bertha (Ruby) Baum. Ruby grew up/ lived in Susquehanna and in the year of 1920 it had a population of approximately 197,837 people.  

Being from Pennsylvania Ruby grew up around mines, so up until the time he joined the military he worked with his father and younger brother as a miner. He also only had completed up to his second year of high school which was higher than both of his parents had received which was 8th grade. Ruby was only 20 at the start of the war. On October 9th, 1940, at the age of 21 he enlisted in the Army in Harrisburg, Pa. He was unmarried at the time of his enlistment and remained so leaving his father Freman as his next of kin when he was deployed.  

This is the 1930 United States Federal Census that shows Ruby and his families ages, jobs, marital status, birthplace, and level of education.

This is a picture of the Susquehanna Coal Mine which is very much like what Private Ruby, his father, and brother worked in.

This is part of the 1940 census which was right before Ruby enlisted into the army. This picture shows  his job, how much he was making, where he was living, and  what grade he finished high school at.