Why was industrialization concentrated in the northern United States until the mid-twentieth century? The South lacked infrastructure. Northern governments subsidized industry. Pay rates were lower in the North. Unions prevented industry from moving south. The South was politically isolated.

 The South lacked infrastructure.

Explanation:

The Northern part of the United States was much more industrialized than the South and this contributed in no small part to the Union victory during the Civil War.

The major reason for this was the extensive infrastructure that had been built in Northern states such as Railroad network and the ship building industries of New England. With such infrastructure providing access to markets, more industries were set up in the North to take advantage of this accessibility.