congregate
To gather together in a group for a purpose.
To congregate means to gather together in a group. When students congregate in the hallway between classes, they cluster together to talk with friends. When birds congregate on telephone wires before migrating south, they collect in large numbers, preparing for their journey.
The word suggests coming together for a reason or purpose, even if it's just to be near others. People might congregate at a park on a sunny day, or in the cafeteria at lunchtime. Animals congregate at watering holes during dry seasons. Fans congregate outside a stadium before a big game.
It's different from just happening to be in the same place: when people congregate, there's usually something drawing them together, whether it's a shared interest, social connection, or a common need. The related noun is congregation, which often refers to people who gather for religious worship, though it can describe any assembled group.