It was a Ford plant in Canada. Started out making Falcons in the 1960s. When they shut down, it was Crown Vics. There's a lot of why but some of it was an agreement between the U.S. and Canada that some auto production would have to be in Canada for the companies to sell cars there. When that agreement was found to be illegal, it meant the manufacturers could consolidate production elsewhere.
The plant had been making full sized rear wheel drive cars. It might have been a billion dollar project to convert it to something more modern. It wasn't money Ford was willing to invest.
Here's an elegy.