<P> Both railroads soon instituted extensive upgrade projects to build better bridges, viaducts and dugways as well as install heavier duty rails, stronger ties, better road beds etc . The original track had often been laid as fast as possible with only secondary attention to maintenance and durability . The primary incentive had been getting the subsidies, which meant that upgrades of all kinds were routinely required in the following years . </P> <P> The Union Pacific would not connect Omaha to Council Bluffs until completing the Union Pacific Missouri River Bridge in 1872 . </P> <P> Several years after the end of the Civil War, the competing railroads coming from Missouri finally realized their initial strategic advantage and a building boom ensued . In July 1869, the H&SJ finished the Hannibal Bridge in Kansas City which was the first bridge to cross the Missouri River . This in turn connected to Kansas Pacific trains going from Kansas City to Denver, which in turn had built the Denver Pacific Railway connecting to the Union Pacific . In August 1870, the Kansas Pacific drove the last spike connecting to the Denver Pacific line at Strasburg, Colorado and the first true Atlantic to Pacific United States railroad was completed . </P> <P> Kansas City's head start in connecting to a true transcontinental railroad contributed to it rather than Omaha becoming the dominant rail center west of Chicago . </P>

When did they finish building the transcontinental railroad