How were the governors of the Roman provinces selected?

During the Republic the provincial governors where selected by the senate either by lot or through a senatum consultum (senatorial advice). The governors of a border province which needed a permanent military garrison were called proconsuls. They called proconsuls. They were former consuls and had the power to command the legions stationed in his province. The governor of the other provinces was called propraetor.

When Augustus, the first Roman emperor, created rule by emperors he reached a settlement whereby the senate retained responsibility for the older provinces of the empire and he assumed control over the newer border provinces. Since most of the legions were stationed in the border provinces, this gave Augustus control of most of the army. The two types of provinces were called senatorial and imperial provinces. The emperor appointed the governors of the latter provinces. He was called legatus (legate).