It is literally at the border with Canada. I had a delivery and they sent me to the other gate which is located on 8th st coming from 3st. But you have to.check in in the small yellow brick building first which is located on your left just before the border checkpoint on 2nd ave right before the railroad. Here's the screenshot of that delivery gate on 8th st.

Complicated to get in but when you do the rest is easy.Use a street on left side to park just before customs and you will see the plant entrance this is where you go to check in