Why were slave states for and free states against annexation of Texas?

It would throw off the number of slave states against free states (which would give one side more power over the other). It was unclear which one Texas was going to be at the time

for the united states of america, 1945 to 1964 was a time of high economic growth and general prosperity. it was also a time of confrontation as the capitalist united states and its allies politically opposed the soviet union and other communist countries; the cold war had begun.

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