With more than 170 still missing, communities must reconcile how to pick up the pieces around a waterway that remains both a wellspring and a looming menace.

The Guadalupe River has a history of deadly flooding. Here is a look over the decades. (AP video Marshall Ritzel/Albee Zhang)

In what experts call "Flash Flood Alley," the terrain reacts quickly to rainfall steep slopes, rocky ground, and narrow riverbeds leave little time for warning.

At least 161 people remain missing in Kerr County, Texas, as authorities and volunteers search the Guadalupe River for victims.

Rescuers searched the Guadalupe River for survivors of the Texas floods that killed more than 100 people over the July Fourth holiday weekend, with an unknown number of people still missing. The basin area was crowded with families and campers preparing to enjoy the holiday when pounding rain brought about catastrophic flash floods just before dawn Friday.