Most rivers east of the Rocky Mountains drain into the Mississippi River drainage system and then into the Gulf of Mexico through New Orleans, Louisiana. Some drain directly into the Gulf (the Trinity River in Texas being one) and others drain directly into the Atlantic Ocean.
Thereare canyons east of the Rocky Mountains, but they are small compared to those in the Rockies. The Rockies have had a geologically recent uplift, so the canyons carved by the rivers are relatively young (thus well defined) and deep. Canyons in the east are smaller and have had time to be substantially eroded.
the rockies are located between the Rio grande in the south & the liard river in the north & of course they themselves shed dozens of rivers to their east & west perhaps most notably the Missouri & Columbia systems respectively
rivers.
Yes.
Snake Rivers
Yes.
Most of the rivers originates from east flow towards south or sourtwest but only Narmada & Tapi rivers flow from east to west because of the faulted zones and drain into Arabian sea. ( if you know better answer than this please add). and it also passes through a rift valley between vindhya and satpura ranges
the Colorado Rockies, and rivers
The adverb is mainly. It modifies the verb "drain" to say that the rivers do not entirely drain into the valley.
Continental Divide
Gulf of Mexico
Columbia and the Snake Rivers