My guess is Hemp Dogbane. The milkweed "family" has 140 species; all have milky sap. Add red stems, branching, downward-facing pods, and hemp dogbane comes up.
![enter image description here](
The flowers are white, not perfectly like common milkweed, and the pods hang down.
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A photo with flowers and pods can be found here.
Hemp Dogbane is common throughout the country.