Losing power for a week over the entire nation would devastate the economy.
For a week? It could be a lot longer than that. Every electronic device could be destroyed even if power were restored.
EMPs can also occur naturally so there is no reason not to harden the infrastructure to be protected against such an occurrence.
EMP is like out running a bear. You only have to out run your neighbors. :-)
A few days, maybe ...
We were out for nine days once, my wood stove worked perfectly...many people had generators. The communities all pulled together, and helped out the older folks.