Chicago Mayor Rahm Emanuel was front and center Thursday at the groundbreaking for a new $100-million CRRC Sifang America rail car assembly facility on the city’s Southeast Side.

The new plant, when completed in the spring of 2018, will be where the Chicago Transit Authority’s newest rail cars, the 7000-series, will be assembled. The project will create more than 300 new construction and skilled factory worker jobs, according to the city officials.

The new CTA car assembly facility also is of historic…