Safest Asset during Great Depression

There is a very good book on the Great Depression in 1930s - 1940s. The book is 'The Great Depression: A Diary' by Benjamin Roth. 

The book is actually a diary of events during the Great Depression. The author was a lawyer. He 

had months with no income during Great Depression. 

From the book, what was the safest asset during Great Depression? 

It is the treasury bonds (i.e. government bonds). 

Other assets such as equities, corporate bonds, farmland, houses have lower prices. Cash in 

banks may face withdrawal issues during bank runs. 

Another interesting trend during Great Depression was that it become fashionable to save more 

and spend less. People compared with each other on how much they save.