Hi ugh What Doc?? For me to answer the question
This is known as the Anaconda Plan.
This military strategy, developed by Union General Winfield Scott, was meant to starve the Confederacy out of their resources. Essentially, Scott felt that if the Confederacy could not trade for goods with other countries they would not be able to survive. This is due to the Confederacy's reliance on cotton as their main cash crop.
This strategy helps to explain why the US wanted to blockade trade with other countries as well as why the Union wanted to control the Mississippi River, as they knew control of this waterway could negatively impact the Confederacy's ability to transport/obtain resources.
Unions forced employers to raise wages and improve working conditions or they wouldn't have laborers. Unions used picketing, protesting, and boycotting to get what they wanted. Through unity, unions helped the working man get what he deserved.
Contain the spread of communism
A lot of reasons while others were struggling with monarchy and oligarchy etc. they didn't want to and they did prefer independence.