Tolong jelaskan mengenai Bandar kembar dari Portland, Maine dalam bahasa melayu

Portland mempunyai empat kota kembar, seperti yang ditetapkan oleh Sister Cities International (SCI):

Michael C. Connolly. Seated by the Sea: The Maritime History of Portland, Maine, and Its Irish Longshoremen (University Press of Florida; 2010) 280 pages; Focuses on the years 1880 to 1923 in a study of how an influx of Irish immigrant workers transformed the city's waterfront. John F. Bauman. Gateway to Vacationland: The Making of Portland Maine''(University of Massachusetts Press: 2012) 285 pages; Explores the socio-economic, political and cultural history of Portland emphasizing the evolution of the city's built environment after the fire of 1866.