By one estimate, the project cost roughly $60 million, about $1.2 billion in today's money, though other sources put the amount even higher. While the railroad's construction was a mammoth undertaking, its effects on the country were equally profound.

The construction of the First Transcontinental Railroad in the 1860s was a monumental financial undertaking that cost approximately $100 million at the time, which, when adjusted for 2026 inflation, is roughly equivalent to $2.5 billion to $3 billion. This figure, however, only scratches the surface of the true economic cost, as the project was heavily subsidized by the U.S. government through the Pacific Railway Acts. The government provided massive land grants—over 175 million acres—and issued government bonds ranging from $16,000 to $48,000 per mile of track depending on the difficulty of the terrain. The Central Pacific and Union Pacific railroads faced staggering expenses for labor, especially with the employment of thousands of Chinese and Irish immigrants, and the logistical nightmare of transporting iron and supplies across vast distances. While the raw dollar amount seems modest by modern infrastructure standards (where a single subway line can cost billions), the project represented a significant portion of the U.S. national budget in the 19th century and effectively revolutionized the American economy by connecting the Atlantic and Pacific coasts for the first time in history.