In May 2023, a delegation from Plymouth County, Massachusetts, traveled to Donegal County, Ulster, Ireland, to sign a sistership agreement between both counties. Plymouth County, Massachusetts, has a population of over 530,000 people, with over 33% of that population being of Irish ancestry. 

This agreement allows for collaboration on topics such as economic development, the Blue/Green Economy, Tourism, and Culture. 

As part of the Plymouth County sister county program with County Donegal, Ireland, Plymouth County will host three events at the end of May to celebrate the sistership program.