In order to control the population and mercantile activities of the Ager, the Romans founded the coastal colonies of Sena Gallica (Senigallia), Ariminum (Rimini), Pisaurum (Pesaro) and Fanum Fortunae (Fano). The administration of the inland was organized in 232 BC by the Lex Flaminia de agro Gallico et Piceno viritim dividendo, which created a network of prefectures (praefecturae), some of which, in the mid-1st century BC, were granted the status of municipia: Aesis (Jesi), Suasa, Ostra, and Forum Sempronii (Fossombrone).
The construction, in 220 BC, of the Via Flaminia shifted the relative position of the Ager, which was now connected to the see of power by the consular road that traversed it along the Metauro river valley.
Later administrative organization
Later, under emperor Theodosius I, the territory was split again (this time from Picenum, which became the province of Picenum Suburbicarium), and became part of the province of Flaminia et Picenum Annonarium. In this new name, which for the first time included the word "Picenum", some have seen an acknowledgement (albeit belated) by Rome of the Italic people known as the Piceni, which had lived in the area between the 10th and 4th century BC.
- Nereo Alfieri, Le Marche e la fine del mondo antico, in Atti Mem. Deputazione Storia Patria delle Marche. 86, 1983, pp. 9-34.
- P.L. Dall'Aglio - S. De Maria - A. Mariotti (eds.), Archeologia delle valli marchigiane Misa, Nevola e Cesano, Perugia 1991
- Nereo Alfieri, Scritti di topografia antica sulle Marche, a cura di Gianfranco Paci, Editrice Tipigraf, 2000, ISBN 88-87994-09-9
- Mario Luni (ed.), La Via Flaminia nell'ager Gallicus, Urbino 2002