The Transcontinental Railroad began laying track east from Sacramento, California, in 1863 and west from Omaha, Nebraska, in 1865; the two lines eventually met in Promontory Summit, Utah, in 1869. One of the train towns, Ogallala, Nebraska, consisted of only a section house and water tank alongside newly laid track. Over the next few years, train towns along the tracks of the First Transcontinental Railroad will be celebrating 150 years of railroad heritage. This investigation presents a mathematics and history interdisciplinary unit for Algebra 2 students that has proved to be a rich modeling experience grounded in this significant historical event. The unit highlights four Standards of Mathematical Practices (SMPs) of the Common Core State Standards for Mathematics. A bibliography is included.