Robert,

    On the old STMFC Yahoo list I wrote about what might have been the origin of the demise of bobber cabooses.

      As I recall finding, there was a bobber caboose in Washington State on a stopped train that was run into by a following train. The caboose was reduced to “kindling” however one of the crew was trapped in the wreckage. There was a lit coal stove in the caboose wreckage that soon spread its fire to the wood of the splintered caboose and the cries of a trapped crew member trapped in spite of the efforts of others to free him. (1912-1914 +/-)

     Newspaper clippings found in my railroad's files told of the shrieking of the victim being burnt alive clearly being heard by onlookers who could not clear timbers fast enough due to the intensity of the spreading blaze as the above was happening, and the horrific account was carried nationally. This same newspaper report and the nationwide public response to it were listed by further letters in the railroad file as the basis of the “24 foot” caboose rule. (Recall also that in this date frame railroad switchmen would still be familiar with link and pin coupling and a railroad man was at that time known by his missing fingers.)  

The letters relate that the 24-foot length was chosen so that two trucks were required. However, steel underframes were not required. Only that buffing forces of a certain threshold were met. Letters between the officers and the mechanical forces lament that the size of wood truss required to meet this this were as costly as steel underframes and would require major rebuilds of the caboose to install them and the railroad might as well install steel underframes at shopping intervals. The steel initially would cost marginally more however lower shopping costs to install them offset that to some degree. 

Now here is where it gets varied.

    Each state the NP ran through established their laws governing the cabooses and these rules did vary from state to state. Minnesota and Washington had the most comprehensive laws, followed by Montana (of which the pusher districts of the Rocky Mountains might have had some influence.) Oregon, North Dakota and Idaho lagged behind the others.

    In the case of the NP, they first put steel sills on cabooses used in mainline pusher districts. Pusher districts can and did exist outside of mountainous regions. This is true on any railroad climbing out of the Great Lakes basin, or the Mississippi River basins. North Dakota had several pusher districts.

This eliminated to some degree old bobbers. Others simply went away because of age.

    By the 1920s, the NP also standardized that all mainline and major branchlines should have steel sills. And all of that did take time so other cabooses did soldier on in use meanwhile. Letters in this file relate to government officials that progress was being made and in that the officials should find comfort in that. Letters from union officials relay about some conductors reporting being assigned boxcars as offices so the truth is somewhere in between.   

      Across the US, the response by other states was also varied, however it did seem to follow red state/blue state politics of those time frames and at that I’ll leave it there.

As last comments, I had seen in this same file noted above (actually more than an inch or so thick) that some older cabooses were sold off to minor logging railroads, so they could have had lives well beyond the timeframe you ask about. Cabooses are non-interchange equipment in this lists time frame, and as such I found NP cabooses that were retired, arch bar trucks and wood frames intact, after this lists end date since they are not subject to interchange rules.  All in yard service and quite close to a car shop it should be noted.     

                                                                                                                                                                                                                                  James Dick - Roseville, MN