Editing First transcontinental railroad (section)

===Rail standards===
[[File:First Day Cover Sc922 75th Anniversary First Transcontinental Railroad May 10, 1944.jpg|thumb|left|upright=0.9|First Day Cover for the 75th Anniversary of the Driving of the Last Spike (May 10, 1944)]]

At that time in the United States, there were two primary standards for track gauge, as defined by the distance between the two rails. In Britain, the gauge was {{Track gauge|ussg|allk=on}}, and this had been adopted by the majority of northern railways. However, much of the south had adopted a {{Track gauge|5ft|lk=on}} gauge. Transferring railway cars across a [[break of gauge]] required [[Bogie exchange|changing out]] the [[Bogie|trucks]]. Alternatively, cargo was [[Transloading|offloaded and reloaded]], a time-consuming effort that delayed cargo shipments. For the transcontinental railroad, the builders adopted what is now known as the [[standard gauge]].<ref name="daspit">{{cite web|last1=Daspit|first1=Tom|title=The Days They Changed the Gauge|url=http://southern.railfan.net/ties/1966/66-8/gauge.html|access-date=10 October 2016}}</ref>

The [[Bessemer process]] and [[open hearth furnace]] steel-making were in use by 1865, but the advantages of steel rails which lasted much longer than iron rails had not yet been demonstrated.{{citation needed|date=October 2016}} The [[Rail profile|rails]] used initially in building the railway were nearly all made of an [[iron]] flat-bottomed modified [[I-beam]] profile weighing {{convert|56|or|66|lb/yd|kg/m|1}}.{{citation needed|date=October 2016}} The railroad companies were intent on completing the project as rapidly as possible at a minimum cost. Within a few years, nearly all railroads converted to [[Rail profile|steel rails]].{{citation needed|date=August 2022|reason=It seems "within a few years" is far too vague to be useful. What is a "few"?  10 years?  30 years?  75 years?}}