One of the largest and most visible companies investing in U.S. operations is General Electric. The conglomerate is spending $1 billion to expand and upgrade its domestic appliance business in Louisville, Ky., Bloomington, Ind., and Decatur, Ala. Hundreds of jobs previously outsourced to China and Mexico are returning to these sites. In February, GE opened a retooled $38 million water heater manufacturing facility at its Appliance Park in Louisville,...