At a packed congressional hearing in late 1991, Donald Trump painted a bleak picture of the downtrodden real-estate industry—including his own business—as he begged lawmakers for help.

“There’s an expression that we’re using—‘Survive ’til ’95,’ ” when the market might begin to turn around, the Republican presidential nominee told lawmakers at the time. He urged Congress to adopt new tax measures to boost the sluggish industry, adding, “You have to get something going. If it’s not started soon, we’re just going to be in a free...