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.

racism and segregation.

abraham lincoln  (february 12, 1809  – april 15, 1865) was an american statesman, politician, and lawyer who served as the 16th  president of the united states  from 1861 until  his assassination  in april 1865. lincoln led the nation through the  american civil war, its bloodiest war and its greatest moral, constitutional, and political crisis.[2][3]  he preserved the  union,  abolished slavery, strengthened the  federal government, and modernized  the u.s. economy.