Monday to Friday, Emma Leng wakes up at 7:50 a.m. in her bright two-story, two-bedroom loft in Shenzhen and arrives at her desk at a medical company in Hong Kong by 9:30 a.m. Her commute is about an hour door to door, thanks to an expanding network of trains connecting the two cities.

The 29-year-old is among a growing number of young white-collar professionals trading expensive, cramped quarters in Hong Kong for less pricey and roomier digs in Shenzhen, a sprawling city some 17 miles (27 kilometers) north that’s often tagged the Silicon Valley of China. Additional perks include cheaper, round-the-clock food delivery options and cleaner air.