How were concert tickets purchased and obtained in the early to mid-1900s?

Concerts took place in an auditorium or a theater. There was a little room beside the entrance specifically for selling tickets. It was called "the box office" and the term is still used although the room does not always exist. Yes, people lined up at the entrance and bought their tickets just before the show started. Typically the audience numbered a few hundred people. It was not until the Beatles that concerts were held in football stadiums.