Shamrock’s historic and symbolic US roots
It represents a shared history between the countries.
St Patrick’s Day was celebrated in America first, in 1790, by Irish businessmen. Irish men and women fought for US independence, and on both sides of the civil war. Latterly, Bill Clinton and George Mitchell influenced our history. In political speak, I’m sure you could call it ‘access’ or ‘a photo op’, but symbolism and history say otherwise.