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In page Berlin:
"From 1865 to 1976, Berlin operated an expansive pneumatic postal network, reaching a maximum length of 400 kilometers (roughly 250 miles) by 1940. The system was divided into two distinct networks after 1949. The West Berlin system remained in public use until 1963, and continued to be utilized for government correspondence until 1972. Conversely, the East Berlin system, which incorporated the Hauptelegraphenamt—the central hub of the operation—remained functional until 1976.[citation needed]
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