Why did geographical barriers such as rivers and mountains limit settlement in colonial north america?

President clinton, on the fortieth anniversary of the events in arkansas surrounding the "little rock nine," stated that "when the constitutional rights of our citizens are threatened, the national government must guarantee them." this principle was the basis for using federal authority in: the expansion of voting rights to women. the passage of the civil rights act of 1964. the passage of the americans with disabilities act. all of the choices.