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:

2686-2181 bce-- "egyptian civilization developed along the nile river in large part because the river’s annual flooding ensured reliable, rich soil for growing crops."

1069-664 bce-- "ancient egyptians developed wide-reaching trade networks along the nile, in the red sea, and in the near east."