Final answer:
The true statement is that (B) Congress considered linking the continent by rail before the Civil War.
Step-by-step explanation:
Among the statements provided regarding the history of the American railway system. This anticipation led to the initiation and completion of the First Transcontinental Railroad. Financed largely by a federal land grant in 1864, the Union Pacific and Central Pacific railroads laid tracks between Omaha, Nebraska, and Sacramento, California. The connection was solidified with the legendary driving of the Golden Spike at Promontory, Utah on May 10, 1869.
The assertion that by 1860, there were less than thirty thousand miles of railroad is incorrect as by that time, there was significant growth of the rail network.
Moreover, the suggestion that railroads experienced rapid expansion throughout the United States in the 1820s is false since the real boom occurred later in the 1840s and 1850s. Likewise, the claim that a member of the state constitutional convention believed connecting California by rail would be detrimental is unsupported by historical facts.
Lastly, while there were indeed military surveys that recommended routes for a transcontinental railroad, a report by the Topographical Corps specifically endorsing two routes is not well-documented.