American manufacturing is gaining momentum.

Job gains are up so far this year after being down last year. The latest industry figures released Monday show factory owners are feeling good.

The ISM manufacturing index -- a key measure of the industry's health -- showed manufacturing grew for the eighth straight month. The index hit 54.8% in April. Any reading above 50% means the sector grew and anything below that mark means it shrunk.

President Trump is squarely focused on increasing the number of manufacturing jobs in America. While the start of the year is good news, Trump faces an uphill battle to significantly add manufacturing jobs.

There are currently about 12.4 million US manufacturing workers. That's up from the low point of 11.4 million in early 2010. Despite the recent gains, manufacturing jobs have been on a decline for years and are well below the 17 million factory jobs held in 2000.

Related: US manufacturing jobs at 1940s levels

Trump blames bad trade deals for the severe decline in manufacturing jobs. A trove of research points at automation and machines as the chief job killer in manufacturing.

Economists like to point out that even though there are fewer jobs, production keeps going up. US manufacturing production is at an all-time high, suggesting that firms can produce more with fewer workers -- an outcome of automation.

However, there's deep resentment in much of America's Rust Belt against trade deals such as NAFTA -- between the US, Mexico and Canada -- as the primary culprit of manufacturing job losses.

Manufacturing has added nearly 50,000 jobs so far this year. That's far better than the 16,000 manufacturing jobs lost last year. Job gains have been reported in each month so far this year.

New jobs numbers come out Friday, but they may not be that good: the ISM index for manufacturing employment declined in April compared to March.