Police ensure that cross-border trade and exchanges bring residents the best of both worlds. Zhao Yimeng reports from Dongxing, Guangxi Zhuang autonomous region.

Editor's note: This is the fifth in a series of stories about China's border patrol guards, focusing on the challenges they face and their work to keep the country safe, prevent trafficking of drugs and people, and maintain friendly relations with their counterparts in neighboring countries.

Every morning, Beilun Bridge in Dongxing, Guangxi Zhuang autonomous region, sees thousands of Vietnamese and Chinese crossing the border, which is marked by a red line that runs across the middle of the structure. When the border post opens at 8 am every morning, people cross, hauling heavy bags on their shoulders or dragging luggage behind them.