How was the economy of the south in the 1850s connected to the culture of slavery?
the building of railroads encouraged enslaved people to do construction work.
the growth of industry in the south diminished the need for enslaved labor.
the agricultural economy depended on enslaved labor for its survival.
the main source of income for farmers was the enslaved labor trade.

During slave trades the south prospered by slavery, cotton, and food product sales. This was the norm till the civil war happened. When the southern economic collapse happened leading to the reconstruction period. The slavery changed from farming to rail ways where not just blacks but many cultures were forced into labor. This practice continued till the early 1900's when rail roads went to other industrial means to build the rail empire.