According to the text, manufacturing is a significant part of the US economy, contributing $2.3 trillion in GDP and employing 12 million people. It represents just 11% of the US gross domestic product and has declined in comparison to other sectors over the years. However, US manufacturing still drives productivity growth, exports, and private sector R&D. Despite a decline in its share of total nonfarm employment, manufacturing production has historically grown in line with real GDP. This is especially evident in the industrial revolution known as Industry 4.0, which has transformed global manufacturing and accounts for 17.5% of global GDP. Furthermore, the US manufacturing value added, as measured in constant 2015 dollars, is 16.3% of global manufacturing value.