It's because the actual army is so small. In that situation the guard can be called to act as a support arm of army which happens because everyone knows the army sucks ass and won't join it. This was routine in the 19th century (though national guard were only called such in NY, it became the national name for state militia in 1903 and officially became mixed state and federal reserve forces in 1933) when the professional US army was small. They basically get called in by the army to be infantry fodder and logistics.
Jesus Christ that's even worse than I thought. 45% of the total force? That's almost half.
It's because the actual army is so small. In that situation the guard can be called to act as a support arm of army which happens because everyone knows the army sucks ass and won't join it. This was routine in the 19th century (though national guard were only called such in NY, it became the national name for state militia in 1903 and officially became mixed state and federal reserve forces in 1933) when the professional US army was small. They basically get called in by the army to be infantry fodder and logistics.