People always seem to be confused by exactly what a park ranger does. That is a difficult question actually, because rangers do so many different things.
Edward Abbey wrote that a Ranger should know how to:
Saddle a Horse
Read a Topographical Map
Follow a trail over slick rock
Memorize landmarks
Build a fire in the rain
Treat a snakebite
Rappel down a cliff
Glissade down a glacier
Read a compass
Find water under sand
Load a burro
Splint a broken bone
Bury a body
Patch a rubber boat
Portage a waterfall
Survive a blizzard
Avoid lightning
Cook a porcupine
Comfort a gelding during the thunderstorm
Predict the weather
Dodge falling rock
Climb out of a box canyon or
Pour piss out of a boot!
Abbey served as a seasonal park ranger in Utah during the 1960's.
Rangers have always had a wide variety of jobs in our National Park system. As time as progressed, rangers have become more specialized. In 1976, specific rangers were designated to perform law enforcement. Before that, any national park service employee had police powers. After the 1970 Yosemite Stoneman Meadow riot, this caused the National Park Service to rethink its law enforcement function. The General Authorities Act gave certain rangers law enforcement powers.