Its attack of Fort Sumter against the Union forces started the Civil War (1861–1865).Confederate defeat led to the impoverishment of the South and the abolition of slavery.However, when white Democrats regained their power in the South in 1877, often by paramilitary suppression of voting, they passed Jim Crow laws to maintain white supremacy, and new disfranchising constitutions that prevented most African Americans and many poor whites from voting.This continued until gains of the Civil Rights Movement in the 1960s and passage of federal legislation to enforce constitutional rights were made.
Economic growth in terms of overall GDP was even greater.
The United States became the world's leading industrial power at the turn of the 20th century due to an outburst of entrepreneurship in the Northeast and Midwest and the arrival of millions of immigrant workers and farmers from Europe.
The national railroad network was completed and large-scale mining and factories industrialized the Northeast and Midwest.
The expansion of slavery was increasingly controversial and fueled political and constitutional battles, which were resolved by compromises.
Slavery was abolished in all states north of the Mason–Dixon line by 1804, but the South continued to profit off of the institution, mostly from production of cotton.