What happens when a foreigner gets a traffic fine in the United States?

I have some personal experience with this. My aunt from China came to visit and after spending some time in the Bay Area (where it is nearly impossible to speed on the highway, and when you do the police are rather lenient) she attempted to drive to Las Vegas. In Barstow she got pulled over for speeding.

My Aunt had a Chinese driver's licence and passport in her possession and was legally in the United States on a tourist visa.

The Officer wrote her a ticket for speeding. The ticket noted her passport number and English name. Without an address on record the officer will give you a written appearance date a a few days later in the local courthouse. I called and requested an extension (90 days). At a later date I then called and was able to pay over the phone with a credit card to clear up the ticket. No actual appearance was required.

The officer did not demand any immediate payment or confiscation of papers and was satisfied with recording her identification numbers.

Since another question has been linked to this, which I feel isn't a totally duplicate question, and nobody has raised the issue on this question, I'd like to add some information about other consequences of speeding that a typical foreign violator might incur that haven't been raised previously.

If you are driving a rental car, the registered owner of the car is of course the rental agency. Typically the rental agency will receive the fine and will normally be required to notify the authorities who was driving. They will do so, providing the state requires it, pay the fine, add on a processing charge and then charge the driver using the credit card on file.

[Note: The info in the above paragraph is only true for parking tickets because parking tickets are issued to a car. A speeding ticket issued by an officer in person is issued to the driver. Not a car.]

Of course credit cards expire, are reported stolen, etc., but that does not normally prevent a charge being made on them. The rental agency will charge the closed/expired credit card and the credit card company will redirect this charge to another card related to it. If it is not possible to locate the card owner then it's likely that the deficiency will be raised to credit reporting agencies and the rantal company will be alerted. After attempting to contact the driver, they will probably offload this debt to a debt-collection agency.

In the end, evading fines is not something that usually does you any good. Sometimes you might get away with it, but if you aspire to have a good credit history in order to buy a house, a car, other assets are obtain credit cards in the future, this will soon come back to haunt you.