SHENZHEN, Jan. 4 (Xinhua) -- The southern Chinese city of Shenzhen saw over 250 million inbound and outbound visits in 2018, compared with 241 million visits in 2017, the city immigration office said Friday.

Up to now, over 179 million passengers have benefited from the city's self-service custom clearance. Currently, more than 70 percent of Shenzhen's custom clearance are self-service.

Shenzhen, as one of China's busiest ports that borders Hongkong, has continued to enhance its customs efficiency, said an official with the office.

According to Shenzhen customs, the city has seen a total of 4.2 billion inbound and outbound visits from 1978, the beginning of China's reform and opening up.