 The development of the railway line that became the LA&SL began in 1871 when the Utah Southern Railroad began laying track southward from Salt Lake City.The Utah Southern, controlled by the larger Union Pacific Railroad (UP), built a line to a station known as Juab, Utah, in 1879.From there a second UP subsidiary known as the Utah Southern Railroad Extension took up the work, completing trackage as far as Milford, Utah, in 1880.