What type of industries employ most people in the US?

service sector (retail, transport, construction, etc). The manufacturing sector are what make nations developed (industrial revolution, modern day china, etc), and agricultural dependent nations are the poorest of the poor.

America is strong in all three areas but its manufacturing sector is diminishing at an alarming rate which is causing so much poverty in the country. This is having an effect on the service sector which depends on the manufacturing sector.

If things continue at this pace the U.S. will become a developing nation in the next few decades, probably sooner.