The number of ships waiting to move through the Houston Ship Channel on Thursday morning had fallen by 20 from the day before as the cleanup of a Saturday oil spill in Galveston Bay continued to gain momentum, the U.S. Coast Guard said. A total of 67 ships were waiting on Thursday to sail to and from the port of Houston along the waterway through which vessels carry crude oil to one-tenth of U.S. refining capacity, according to the Coast Guard. Of Thursday’s total, 46 were waiting to enter and 21 waiting to exit. Not all of those ships are tankers, there are also container ships and bulk carriers, the Coast Guard said. The channel was shut on Saturday when a Kirby Inland Marine fuel oil barge collided with a cargo ship near the entrance to Galveston Bay, spilling 4,000 barrels or 168,000 gallons (636,000 liters) of heavy, black fuel oil. The channel reopened on Tuesday, though ships have to check in at inspection and decontamination stations along the waterway. The Coast Guard has temporarily banned ships from moving along the channel at night to prevent vessels from spreading the oil to the northern end of the Bay. The Galveston Bay spill is far smaller than the 260,000 barrels, or 11 million gallons, of crude oil that was released when the Exxon Valdez struck a reef in Prince William Sound, Alaska in 1989. (Reporting by Erwin Seba; Editing by Sofina Mirza-Reid)