Is surrogacy a cultural change?

What river valley civilization in the plow

How were the economies of the northern and southern states different? how ere they the same? what factors led them to develop differently?

Which of these was not a key difference between northern and southern states at the constitutional convention? wanting to protect states’ interests vs. a government with strict rules having more, larger cities vs. having fewer, smaller cities wanting to protect agriculture vs. protect industries having many enslaved people vs. using less enslaved labor