There are certain parts of the Chinese internet that have to be seen to be believed. Coming from outside the country, it’s hard to comprehend that Facebook or Google can be completely blocked until you are forced to do without them. It’s tough to fathom how critical the messenger app WeChat is for everyday life until the sixth person of the day asks to scan your QR code — a sort of bar code — to connect the two of you.

What’s happening with cash in China is similar. For the past three years, I have been outside mainland China covering Asian technology from Hong Kong, which has a very different internet culture from the mainland. I knew that smartphone payments were taking over in China, as the statistics were stark: In 2016, China’s mobile payments hit $5.5 trillion, roughly 50 times the size of America’s $112 billion market, according to consulting firm iResearch.

Even so, the attendant cultural shift was graspable only in person. I recently moved to Shanghai and felt the change with cash acutely because my first few weeks in the metropolis of more than 20 million were spent cut out of the system. Because of an issue with my bank, I couldn’t immediately link my account to WeChat, which has become a virtual wallet for so many.

That meant I had to navigate China the way I would have three years ago: with a stack of red 100-renminbi notes.