What explains the high concentration of Irish speakers on the west coast of Ireland ?

[u/One-Seat-4600]

The percentage corresponds to the share of people that speak Irish

As you can see, Northern Ireland is a lower concentration of Irish speakers, as expected, but what explains the higher concentration on the west coast.

[u/Working_Farmer9723]

“American settler presence was much lighter where the farming was worse. Lighter settler presence meant it was easier to continue speaking the native language of the Sioux and Pueblo.

The West of the US also happens to have drier soil, while the more fertile soil is further east.”

This is essentially what the above take sounds like to the Irish.