Idahoers, welcome to our alphabetical list of counties in Idaho A-Z! In this post, we’ll answer the questions: How many counties are in Idaho? What are the 5 largest counties in Idaho? What is the fastest growing county in Idaho? So whether you’re studying for class, interested in geography, or learning some trivia, keep reading for our alphabetical list of counties in Idaho A-Z!
A
Ada
Adams
B
Bannock
Bear Lake
Benewah
Bingham
Blaine
Boise
Bonner
Bonneville
Boundary
Butte
C
Camas
Canyon
Caribou
Cassia
Clark
Clearwater
Custer
D
E
Elmore
F
Franklin
Fremont
G
Gem
Gooding
H
I
Idaho
J
Jefferson
Jerome
K
Kootenai
L
Latah
Lemhi
Lewis
Lincoln
M
Madison
Minidoka
N
Nez Perce
O
Oneida
Owyhee
P
Payette
Power
Q
R
S
Shoshone
T
Teton
Twin Falls
U
V
Valley
W
Washington
X
Y
Z
The 5 largest counties in Idaho by population are Ada, Canyon, Kootenai, Bonneville, and Twin Falls.
The largest county in Idaho by land mass is Idaho County.