If you lived on a border of a country that speaks different languages how is it chosen what language you speak? If you lived on the border do you just learn both languages?
Or is it more if you lived even like 500 meters of a border do you learn the language of the country your in? Do people choose it based on nearest popular city to where they’re at?
Whatever the majority of the people in the area are speaking. Another factor is which side of the border the community interacts with more. If say the city is technically closer to an urban area on the bordering country than it’s neighbor within its own country, then they likely interact more with the former so will speak that language more.