The Gem of Egypt and Silver Spade operated in Eastern Ohio were both larger. Amazing machinery. Operated on electric, they used a dozer to move the "extension cord" around. Really eerie to be around (that's relative, they'd only let you get so close) them when operating. Did get to stand under the Spade once after it was shut down. Absolutely awesome machine.
Now.... The Big Musky operated just a few miles south and west of the Gem and Spade had a even bigger bucket, but it was a dragline and set up on the pit edge whereas the Spade, Gem, and machine pictured above were "shovels" and sat on the bottom of the pit on the coal seam and lifted the blasted overburden up and out of the strip mine.