Colonial era: british
WW1: American
WW2: British (America for the atom bomb... but thats just one weapon. and they massed produced everything else really)
after that: AMERICA!!
Idk d it might be d i might be wrong
7 SEPTEMBER 1822
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If you're looking for the name of someone who studies the stars it would be an astronomer.
Answer:
conserve household products to support the war effort