NEW YORK - The city's letter grading system for food carts and trucks officially launches Friday.

All 5,500 authorized vendors will be given a grade of "A", "B" or "C" based on food safety inspections — just like traditional restaurants.

The Health Department will use a location sharing device to track the carts and trucks when they're due for inspection.

The city is taking steps to protect location data.

It says the information will only be visible to Health Department staffers and will be deleted within 24 hours. 

It's expected to take about two years for all the trucks and carts to be graded.