No jet fuel in NYC?

Delta Airlines is taking me, along with a large group of others, from JFK to SFO. They just announced that the flight will make a refueling stop in Salt Lake City.

I've been on a lot of transcontinental flights and this is new to me. A plane that can't carry enough fuel to fly coast-to-coast is being used by Delta on a New York to San Francisco flight?

There may be other explanations, for example Delta may have lower cost fuel in Salt Lake than in JFK. Or the airline didn't calculate correctly the weight of passengers and luggage. Like me there are many folks on this flight transfering from trans Atlantic flights who typically have bags checked.

Anyway, I will be home later than I hoped.