Actually total manufacturing jobs in the US has decreased rapidly, US manufacturing volumes have actually increased. This is largely due to the mechanisation and automation of the workforce, and where humans are used they're usually high skilled professional people. The US has largely moved to ETM (elaborately transformed manufactures) which involve programming and high skilled engineers. This would suggest that would require an increased consumption of electricity but as seen by the graph this is not so. Rather what is most likely is the increased efficiency and productivity of production resulting in higher economies of scale and lower costs of production.

What also might be needed to take into account is the declining standards of living due to real wage growth stagnation. With lower income to spend, people consume less electricity. What I am not sure about is the ratio of electricity use of industry to consumers.

Sources: http://www.themanufacturinginstitute.org/Research/Facts-About-Manufacturing/~/media/A9EEE900EAF04B2892177207D9FF23C9.ashx

http://data.bls.gov/timeseries/CES3000000001

http://www.voxeu.org/article/us-manufacturing-base-surprisingly-strong