How did the the transcontinental railroad affect the US commerce?

The railroad increased commerce by making shipping easier and cheaper. iron and machinery. Due to the railroads, American settlers were able to travel west in larger numbers.

Explanation:

one of the main reasons was definitely slavery. back in 1861, republican abraham lincoln was elected and ended up being a major influence in the slavery business. slavery greatly affected the texas economy because back in 1845 during the annexation of texas, slaves became a big part of the texas population. many texans that were in favor of the secession influenced groups through party ties.

1. temperance, abolitionist, suffragist