Lincoln means that the United States is unconstitutional if slavery is not abolished. He means to say that preserving the Constitution is abolishing slavery and that this would only bring progress to the United States. Keeping slavery would only wreck the United States.
Hope that helped! Good luck!
Change sister's to sisters'
Change single's to singles
Hi! Welcome to brainly!
You would use a comma, but it should come before but.
Hope it helps fam!
~CoCo<3
