* Ilocano: This is the dominant language in the region, spoken by a majority of the population.
* Pangasinan: This language is spoken primarily in the province of Pangasinan.
* Tagalog: As the national language of the Philippines, Tagalog is widely understood in Region I.
* English: English is also widely spoken in Region I, especially in urban areas and educational settings.
* Other Minor Languages: There are a few other minor languages spoken in the region, such as Kapampangan, Sambal, and Iloko-Tagalog.
It's important to note that the use of each language varies depending on the specific location within Region I. For example, Ilocano is more dominant in the provinces of Ilocos Norte, Ilocos Sur, and Abra, while Pangasinan is more common in Pangasinan.
If you're looking for a more detailed breakdown of languages by specific municipality, you can check resources like the Philippine Statistics Authority (PSA) or the Ethnologue website.