The Francis T. Guelker Log Cabins Collection was assembled by Guelker, with the help of his wife Catherine "Bobbie" Guelker, between 1992 and 2007 and contains photographs and research documenting log structures within 100 miles of St. Louis, in both Missouri and Illinois. Log cabins are the predominant building type, but other structures such as barns, corn cribs, sheds, smokehouses, and churches are also included.

Guelker's research represents an avid collector’s interest in anything related to log buildings. Photographs taken by Guelker show interior and exterior views of log buildings in various states of repair. Some buildings are greatly deteriorated, while others are newly constructed. Accompanying background information for each log building is quite varied and includes correspondence with the owners, newspaper and magazine articles, pamphlets or booklets from historic sites, flyers advertising events held in log buildings, and typed notes documenting Guelker's log building related phone calls and in person visits. In addition, Guelker occasionally received photocopies of land titles and other official records from his correspondents. This information sheds light on the history of the buildings and on the families that built them and owned them. Some genealogical information regarding these families is also included, in addition to articles describing current or past owners' activities outside the realm of log buildings. Guelker also documented the work of those who professionally restore log buildings and reconstruct buildings that have been moved, including Ray Prouhet, Tim Kilby of the County Gentleman, and Bill Hacker.

Information provided for each cabin is neither consistent nor systematic, depending entirely on the information Guelker could gather from his sources and correspondents. Some cabins are identified by their original builder, while others are identified by their current owner, and it is not always clear whether a name refers to a current or past owner. Various degrees of location are provided, ranging from a specific street address to a general city or county. Construction dates are not provided for every building, but seem to range from the 18th century through the late 20th century. Few specific architectural features or styles are noted, with the exception of corner notching styles; dog-trot buildings; and the French-built poteaux-en-terre and poteaux-sur-sole buildings.