The chosen route and destination of the telegram provide strong evidence of the message's importance.
The evidence from the excerpt leads to the inference that the message Zimmermann sent was important because the route the telegram was to take, first to Sweden and then to Washington, D.C., supports the idea that the contents of the message were crucial. This strategic route chosen by Zimmermann to make sure the telegram reached von Bernstorff highlights the significance of the message. The telegram's intended destination in Washington, D.C., and the effort to ensure its safe delivery through a U-boat indicate the importance of the message sent by the German foreign secretary.