LANSING, MI -- In 1960 Detroit was one of the wealthiest cities in the United States and today it's the poorest, said presidential candidate Bernie Sanders in opposing trade deals at a press conference Thursday.

"All that I am here to say today, along with everybody else here, is our trade policies for the last many decades have been an unmitigated disaster," Sanders said.

In Michigan, a state with a rich history of automotive manufacturing, he's using the issue to create space between he and presidential candidate Hillary Clinton, who at one point strongly supported the North American Free Trade Agreement.

Sanders is airing an ad against trade agreements in Michigan.

He said in considering trade agreements on a case-by-case basis he's studied them and found them to be disastrous.

"These trade agreements were pushed and written to a significant degree by corporate America, for corporate America," Sanders said.

In the early 1990s he and U.S. Rep. John Conyers toured a manufacturing area in Mexico. He recounted how American companies had shiny new factories there, but workers were living in cardboard shacks. The low wages for workers in other countries aren't good for people in other countries, Sanders said, just like they're not good for Michigan.

"When you look at Detroit, when you look at Flint... we have lost thousands and thousands of decent-paying jobs," Sanders said.

He said large American companies were moving plants to save a few dollars -- something that has come at the expense of working families.

"It is time to tell corporate America in a very forceful way that they are no longer going to throw American workers out on the streets and build shiny new plants in China, Mexico and other low-wage countries," Sanders said.

Clinton, meanwhile, is delivering a speech on jobs and the economy at Detroit Manufacturing Systems in Detroit Friday.

Emily Lawler is a Capitol reporter on MLive's statewide Impact Team. You can reach her at elawler@mlive.com, subscribe to her on Facebook or follow her on Twitter: @emilyjanelawler.