TULSA, Oklahoma - Oil prices are rising to their highest levels in four years, as crude oil supplies are falling.

In Tulsa, drivers will see the rising cost of crude reflected at the gas pump.

News On 6 checked early Thursday and found prices ranging from $2.43 at Tulsa's Flying J to $2.55 at most Tulsa area QuikTrips.

Industry watchers say oil prices are going up because of concerns over U.S. threats to sanction countries that don't stop importing oil from Iran by November 4th.

The U.S. Energy Information Administration says gasoline prices may have peaked, crude oil supplies are down by more than 9-million barrels last week.  That's the largest weekly decline this year.

The Oil Price Information Service says gas prices will vary a lot this summer and it's all based on the gasoline imports.