The steam engine had the most impact for westward expansion. This invention made travel by water and land so much faster and cheaper. This allowed boats to go up stream witch was impossible before. The early 1800's was a big time for steamboats, after the invention there were thousands of miles of canals dug for it. "The steamboat solved the upstream travel difficulty. The boat gets its power from a steam engine Fulton made."
After the very popular steamboat, some one made the steam engine for trains. this also allowed fast travel across land. This was so much cheaper because the rails were easier than digging the canals. This allowed more people to travel west. This also let supplies be shipped to the west. "The railroad era in America began and people and goods were now moving across the country faster than ever"
This helped the country expand rapidly. This effected so much because there was a massive in flux of money and it helped many people have jobs and money for there family with these new jobs. You could go anywhere in the country within days, Before it would have been a long painful trek that would take months. This spread encouraged the American dream of rags to riches by letting people start there own farms and buisnesses every where.