​In 2005 Portsmouth celebrated the centennial of the Portsmouth Peace Treaty which ended the Russo-Japanese War and earned President Theodore Roosevelt a Nobel Peace Prize. The Portsmouth Peace Treaty Anniversary Committee (PPTAC) celebrated the historic role local people played as citizen diplomats during the peace conference.

Since then, commemorations recognizing the importance of the Portsmouth Peace Treaty to New Hampshire history and people-to-people or citizen diplomacy have taken many forms:

2006 100th Anniversary of Theodore Roosevelt's Nobel Peace Prize
2007 First Seacoast Wind Ensemble Treaty Anniversary Concert, Labor Day/Portsmouth Peace Treaty Parade, Portsmouth Peace Treaty Forum with Amb. Dennis Ross
2008 Seacoast Wind Ensemble Treaty Anniversary Concert, "Flags Over Portsmouth" Photograph Exhibit, Portsmouth Peace Treaty Forum with Amb. Samantha Power
2009 Seacoast Wind Ensemble Treaty Anniversary Concert, Portsmouth Peace Treaty Forum Obama Nobel Peace Prize 
2010 Bill Declaring Portsmouth Peace Treaty Day and photo recreation
2011 Order of the Rising Sun
2012 100 Years of Cherry Trees
2013 Historical Marker Dedicated, Portsmouth Peace Treaty Living Memorial Cherry Trees
2014 Sister City Connections, Pecha Kucha Portsmouth "Suddenly, Bloom!"
2015 110th Treaty Anniversary Commemorations with Russian and Japan, Sister City Visit
2016 110th TR Nobel Anniversary, 60th Anniversary Nichinan Sister City Agreement, Portsmouth Peace Treaty Forum with Graham Allison & Fiona Hill
2017 Sister City Visits and Pen Pal Project
2018 Sister Cities Historical Marker Dedicated, Raylynmor Opera "Madame Butterfly"
2019 Saving Carey Creek Farm, Portsmouth Peace Treaty Forum with Jake Sullivan
2020 Portsmouth Peace Treaty Forum with Joseph S. Nye. Jr. (virtual)
2021  Carey Cottage talk
2022  Christ Church talk
2023 Sister City Visit, Diplomats in Portsmouth exhibit for Portsmouth NH 400th
2024 Portsmouth Peace Treaty Forum with Fiona Hill
​2025  120th anniversary
​