Identifying numbers are assigned to observation stations by the National Climatic Data Center. New numbers are assigned when a station move is greater than the allowable change in distance or elevation, or there is a change in its post office. These rules are good because the number change occurs only when there are objective reasons to change it. Each change is documented and the system has worked well since its inception in March 1948. A climate observation station‘s period of record often determines its inclusion or exclusion from climate studies. That period of record is obtainable from the National Climatic Data Center online information using the station's number. However, using just that number may significantly delimit the period of record because it may have changed over the years. The needs of a research project may find that less stringent rules could be tolerated. Then the question is, what other station numbers can be combined to constitute a longer period of record while retaining an acceptable continuum of data for the research project at hand? The answer lies in stations' histories. Tracing a station's history is akin to tracing one's family tree. This paper describes the development of station pedigrees to identify a station's ancestral lineage. The techniques used to develop the pedigrees of each of about 400 observation stations in Kentucky are presented. Examples are given of the resulting extension of period of record by decades by combining station numbers without significant detrimental impact on the data.