If you were on social media a week or so ago, there were lots of videos of the “Big Boy,” No. 4014, steam locomotive chugging East. It never made it to Schenectady. When people think of Schenectady, they usually think of General Electric, “The Electric City.” Yet another industrial giant helped shape both Schenectady and the nation: the American Locomotive Company (ALCO). Among the thousands of locomotives built in its sprawling works along the …