It took a while, and a huge investment from the US to avoid the locals flocking to the DDR.

(The Soviets, unable to put in as big an investment, built the wall to stop DDR citizens from making the opposite trip).

The history of the border between the DDR and FRG is quite nuanced and interesting. The Iron Curtain was more of a cooperative effort, especially early on, and especially outside of Berlin.

Worthwhile reading on the subject: https://www.amazon.com/Burned-Bridge-East-Germans-Curtain/dp....

In some ways, the existence of a physical border begat the political and economic division, as much as the other way around!

indeed.