Dense fog has halted traffic to and from Houston-the busiest US petrochemical port at 1:55 am on Wednesday. After an seven-hour halt, ships were sailing both inbound and outbound on the Houston Ship Channel for the first time since morning. Ships had moved only outbound down the channel to clear dock space for inbound ships between 9 a.m. and 12 noon CST. The Houston Ship Channel serves the ports of Houston, Texas City and Galveston, Texas. Refineries in Houston and Texas City account for 13.45% of U.S. refining capacity.