Barbara Conrad received the Cross of the Order of Merit from the Federal Republic of Germany for her decades of leadership with GAST and her longstanding support of the Tulsa–Celle Sister City Partnership.

In 2020, TGA and the City of Tulsa celebrated 40 years of Sister City partnerships with the dedication of the first Sister Cities directional sign at Tulsa Ports, sponsored by Advance Research Chemicals.

Mayor Dr. Jörg Nigge visited Tulsa for several days of meetings and community events that strengthened the long-standing Sister City partnership between Tulsa and Celle.