Unsorted:

Array
(
    [MD] => Maryland
    [PA] => Pennsylvania
    [IL] => Illinois
    [MN] => Minnesota
    [WI] => Wisconsin
    [NY] => New York
)

asort($states) | Ascending order values with keys:

Array
(
    [IL] => Illinois
    [MD] => Maryland
    [MN] => Minnesota
    [NY] => New York
    [PA] => Pennsylvania
    [WI] => Wisconsin
)

arsort($states) | Descending order values with keys:

Array
(
    [WI] => Wisconsin
    [PA] => Pennsylvania
    [NY] => New York
    [MN] => Minnesota
    [MD] => Maryland
    [IL] => Illinois
)

sort($states) | Ascending order values:

Array
(
    [0] => Illinois
    [1] => Maryland
    [2] => Minnesota
    [3] => New York
    [4] => Pennsylvania
    [5] => Wisconsin
)

rsort($states) | Descending order values:

Array
(
    [0] => Wisconsin
    [1] => Pennsylvania
    [2] => New York
    [3] => Minnesota
    [4] => Maryland
    [5] => Illinois
)

ksort($states) | Ascending order by keys:

Array
(
    [0] => Wisconsin
    [1] => Pennsylvania
    [2] => New York
    [3] => Minnesota
    [4] => Maryland
    [5] => Illinois
)

krsort($states) | Descending order by keys:

Array
(
    [5] => Illinois
    [4] => Maryland
    [3] => Minnesota
    [2] => New York
    [1] => Pennsylvania
    [0] => Wisconsin
)