More than 11,000 people spent summer nights beside Han River this year, giving Seoul officials evidence that after-dark leisure can do more than keep people cool — it can benefit the local economy. “Han River Night Camping,” held at Yeouido and Ttukseom Han River parks from Aug. 1 through Aug. 30, drew 3,503 groups and 11,476 people, with Friday and Saturday sessions selling out within five minutes. The overnight program allowed participants to set up tents from 5 pm until 9 am, combining riverside views with delivery food and an escape from Seoul’s summer heat. In a survey of 1,106 participants, 94.7 percent said they wanted the program to return next year, while 80.1 percent said they were satisfied with their experience. Another 90.1 percent said the program helped promote nighttime leisure culture and the local economy. Spending rose with foot traffic in commercial districts surrounding Yeouido, Ttukseom and Mangwon areas, according to an analysis of payment data from four credit card companies. Nighttime pedestrian traffic across the three areas increased 66 percent to an aver