What thing did most river valley civilizations have in common?

answer; people where able to travel across the u.s.a faster than any other mode of transportation,travel time was about a week,from coast to coast

d) the constitution rights of native americans and their right to self-government on reservations

answer; ///i believe that the correct answer is ; hieroglyphs or glyphs; the maya script, also known as maya glyphs, was the writing system of the maya civilization of mesoamerica; as always plz check first..good luck