KARACHI, Pakistan — For three generations, Muhammad Rizwan’s family saw their tiny market stall as their second home, the sons growing up there helping with the stock while their fathers dealt with customers.

Mr. Rizwan, 35, started selling shoes and clothing there as a teenager and had hoped to pass the business down to his son. Today it is a pile of rubble, the result of a government bulldozing operation that began around Karachi’s famous Empress Market and now stretches across the city.

“My grandfather was the first to work in this market — he sold rope back then — and now it seems like I’ll be the last,” Mr. Rizwan said.

The unofficial tent stalls that had long surrounded Empress Market are among the many sites targeted by the Karachi government’s “anti-encroachment” campaign against commerce that spills into the city’s streets and parks. Hawkers and informal structures have become an entrenched part of life in Karachi in the decades since it transformed from a quaint port village into one of the biggest cities in the world, with a population of at least 15 million.