Complex sentence: The West Summit Trail is considerably more popular than the East Summit Trail, mostly because the East Summit Trail involves scrambling up a steep slope; both, however, can be quite overcrowded due to their proximity to Little Rock.
Split into simpler sentences: The West Summit Trail is far more trafficked than the East Summit Trail, partly because the East Summit Trail involves scrambling up a steep slope. Both, however, can be quite overcrowded due to their proximity to Little Rock.