Of course, at all times past and present, the celebrating priest had to consecrate and receive in both species. However, it grew to be the practice, especially as the numbers of Catholics grew quite large, to offer to the people Communion in only one species. The Councils of Constance and Trent made this not just a common practice but a required universal discipline. It was forbidden to do otherwise.
Of course, it was (and is) a discipline, NOT a doctrinal or theological pronouncement. Popes had the authority to make exceptions with an indult, which they did once in a while. It has always been maintained that Christ is fully present, Body and Blood, under each species.
The discipline has been loosened since the Second Vatican Council. The US bishops have chosen to loosen it particularly so here in America, where it is very common in parishes to offer Communion in both kinds. Most parishes I've been to offer it. Of course, it is optional. A certain number of communicants in each parish pass on it.