7 states missing in 1970 1% State Form 1. Why?

Can someone explain why seven states are missing for this sample, specifically? I understand there are multiple samples and te state information may be suppressed in the metro sample, etc. I am wondering why, specifically, there are zero observations for the 1970 1% State Form 1 sample.

The missing states are: Delaware, Idaho, Montana, N Dakota, S Dakota, Vermont, and Wyoming.

Thank you.

Looking at the STATEFIP codes page (after selecting the 1970 state samples) all states are represented in the 1970 1% State samples. I also confirmed this with an extract. To make sure you are using the 1970 1% Form 1 State sample you can check that DATANUM==1 (or DATANUM==2 for 1970 1% Form 2 State sample) for YEAR==1970.

I hope this helps.