What was the main driver of the economy in the North during the Civil War?

The South had great wealth, but it was tied up mainly in the slave economy. By 1860, America's economic worth of slavery surpassed the accumulated income of all the nation's railroads, manufacturers, and banks combined. Cotton rates had been at an all-time high on the eve of the Civil War.

i think it should be slowed colonial western march

a because the britsh thought the ameracans were trators so a