When Charles Dickens wrote A Tale of Two Cities 150 years ago, he said, “It was the best of times, it was the worst of times.” Today, the same thing can be said about two assembly plants owned by General Motors Corp. (GM, Detroit).

A Tale of Two Cities 150 years ago, he infamously penned the phrase, “It was the best of times, it was the worst of times.” Today, the same thing can be said about two assembly plants owned by General Motors Corp. (GM, Detroit).

The automaker just announced plans to shutter its Janesville, WI, facility by the end of this year. At the same time, GM just ramped up production at its retooled Spring Hill, TN, plant.

Until recently, the vehicles made in Janesville, a small town 40 southeast of Madison, WI, were among GM’s most profitable. The plant assembles the Chevrolet Suburban, Chevrolet Tahoe and the GMC Yukon. Those sport utility vehicles (SUVs) helped line the coffers at GM during most of the past decade. But, now that the market has shifted dramatically-full-size SUV sales are down more than 33 percent this year-the old plant is no longer attractive to the company.

That’s too bad, because the facility traces its roots to 1919 and is GM’s oldest factory in the United States. Over the decades, the former tractor plant has cranked out millions of Chevrolet vehicles, such as Caprice and Cavalier sedans, plus a wide variety of half-ton pickup trucks. During World War II, the plant produced 16 million artillery shells.

Meanwhile, 40 miles south of Nashville, TN, folks are playing a different tune. General Motors just spent 12 months and $600 million remodeling its former Saturn factory. The facility’s 1.2-million-square-foot general assembly area was completely rebuilt to produce the Chevrolet Traverse crossover vehicle. As part of the mammoth project, 31 miles of new conveyor systems were installed throughout the plant’s body shop, paint shop and final assembly line. In addition, more than 600 new robots were installed in the 850,000-square-foot body shop.

While the future looks bright in Tennessee, it’s another story for assemblers in Wisconsin. But, maybe this tale of two plants will have a happy ending, unlike Dickens’ novel.

The workforce in Janesville is considered to be one of the best in the auto industry. Perhaps GM’s executives will get smart and decide to retool the factory to build fuel-efficient vehicles. How about assembling the Opel Agila, the Vauxhall Insignia or some other vehicles from GM’s high-mileage European lineup in Janesville?

Then again, maybe the mothballed plant will appeal to an automaker in China or India looking to assemble vehicles in the heart of the Midwest. That’s a tale Detroit hopes will never be told.