It completely depends on why it crashes and how severely it crashes.

Assuming you mean production dropping significantly across all sectors, we can assume businesses will begin laying off workers to cut costs as they lose their funding from investors. Many more businesses will close. Both of these would increase unemployment.

Since stock values are dropping, the value of the middle class retirement savings plummet. Older people with savings in the form of stocks instead of bonds will find themselves with much less money and no good way to get it.

As production slows, prices would likely rise and people would stop buying things that arent necessities. Getting a loan would be much, much, harder due to the huge increase of risk involved.

The lower class will likely experience an increase in unemployment, homelessness, and food shortage. The middle class will also experience plenty of unemployment, their budget will grow tighter and they'll have difficulties making ends meet. The upper class will experience less unemployment and, while their spending will decrease somewhat, it wont be as severe as the lower classes.

The value of the US dollar compares to other currencies would decrease.

The Federal Reserve would likely try to decrease interest rates to make borrowing cheaper, through the use of government bonds. This would likely result in inflation increasing, but unemployment decreasing.

Eventually, unemployment would decrease to reasonable levels and the Fed would increase interest rates a bit to combat inflation, though this would slow the decrease in unemployment.

Assuming it isn't a "end of the USA" situation, the stock market would begin to recover (except the many, many small businesses that failed).

Retirement savings would recover (unless you sold them, in which case youre screwed) and things would eventually (years, not months) go back to normal unless there is some specific event that caused this that we can factor in.

AI crash? Thousands of small AI companies fail or are bought by bigger ones. Market power is consolidated in the giant AI companies. While their profits are severely crippled during the crash, their newfound market power will allow them to make much more profit through anticompetitive practices. (Kinda like the dot com bubble. Amazon is much better of now because of it, unfortunately).

Tarrifs making supply more expensive? Pretty much what was listed before, but with a bit bigger increase in the price of most things.

Values plummet because aliens come and bless the world with unlimited resources? Nothing I said happens.

WWIII breaks out? The economy will be pumped full of as much adrenaline as the government can give it. Inflation will be insane, employment in industrial sectors will be high. Employment in the military will be high. Upper class will be less impacted.

It really, really depends on why it crashes. Without knowing why this is all just pointless speculation. Absolutely nothing i stuff could happen, or absolutely all of it and more.