The 1930 Mexican Census is the most complete census up to that date. It contains a wealth of information and it might be just what you need to find your ancestors.
It has already been several years that ancestry has hosted them and also lets you search them for free.
The only catch is that you do need to create a free account with them. It is a no biggie and it is very simple to create.
Once you create your free account Ancestry will let you browse and or search the 1930 Mexican Census for free. Let me just warn you and also to be honest, some of the 1930 census is missing and personally it has not helped me in my own direct family research since it seems that the municipality of Mier is missing. I did hit a treasure trove with my brother in laws family.
Overall this census only has 90 percent of the population.
So if you can’t find your family on it it might just be the case that, that particular section might also missing.
I hope that this resource helps you.
Here is the link to Ancestry:
FYI: These records are in Spanish.
Let me know int he comments section what you think about this resource and if it helped you out.