Final answer:
The important new technologies that helped grow the country's economy between the 1800s and 1900s were communication technologies, electric power production, and steel production.
Step-by-step explanation:
The important new technologies that helped grow the country's economy between the 1800s and 1900s were communication technologies, electric power production, and steel production.
Communication technologies, such as the invention of the telephone by Alexander Graham Bell in 1876, revolutionized the way people communicated and facilitated business growth. Electric power production, made possible by the development of electrical generators in 1870, transformed US factories and increased productivity. Steel production, with the invention of modern steel in 1856, led to the efficient and cost-effective production of large steel elements, which greatly impacted industrial growth.