The boom in iron and steel production gave which U. S. industry the greatest rate of growth after the Civil War?

The steel industry.

Explanation:

By the end of the 19th century , the steel production in the USA had become massive. In 1901 the U.S. Steel company was formed. It was the largest company of the world then. Tecnological advances had made possible the growth of the steel industry after 1865.

a. because the u.s. was the leading with the most technology, economy, etc. also was teamed with other allies witch boosted the economy and materials to improve technology and use it.