Answer:
Yes it is an equivalence relation
Explanation:
An equivalence relation is a binary relation between two values that are symmetric, transitive and reflexive. In other words, when we say a value x is equal(using "=") to a value y, there is an equivalence relation between them.
Example, given set {x, y, z} where ~ means equivalence:
x ~ y if y ~ z means symmetric
since x ~ y and y ~ z, then x ~ z means transitive
x ~ x means reflexive
Equivalence relations share a common attribute or attributes(example, a satisfying condition)
The above condition that two states are related from the set of all US states if they have a border in common satisfies the condition of equivalence listed hence it is an equivalence relation.
