What does US industrial production measure?

The US Industrial Production Index measures output of electric and gas utilities industries, mining industry, and manufacturing industry. The reference period used while calculating the industrial production index in the US is 2017. You can read about the Index of Industrial Production [UPSC Economy Notes] in the given link.

While calculating the Index of Industrial production in India, the base period is 2011-12 and 8 core industries have around 40% weightage.

Further readings:

1. Merger of NSSO and Central Statistical Office (CSO) to form National Statistical Office (NSO)
2. Core Sectors of the Indian Economy