Something weird happened in the 1980s — and I don’t mean big hair or Spandex: Americans stopped moving. Particularly, the number of Americans who migrate between different states slowed dramatically. Here’s what that looks like in a chart, courtesy of a new National Bureau of Economic Research paper:

Migration from state to state increased sharply in the wake of World War II. It continued to creep up through the 1960s and 1970s, too. But moving started slowing down in the 1980s — and never stopped. “By most measures, internal migration in the United States is at a 30-year low,” the NBER authors Raven Molloy, Christopher Smith and Abigail Wozniak write. “Migration rates have fallen for most distances, demographic and socioeconomic groups, and geographic areas.

What happened? The researchers say it’s not totally clear cut, but do point to a few factors at play. Technological advances have allowed for the expansion of telecommuting, reducing the need for workers to move. Locations have become less specialized and in what kind of goods and services they produce. Even social trends play a role: as fewer Americans get married, the NBER study points to data showing a steep drop in those moving for matrimony. Not enough to drive a decades-long migration decline, they say, but one of a number of factors that may contribute.