Are these states connected?
Wolfram Language (Mathematica), 169 167 bytes
ConnectedGraphQ@Subgraph[Cases[#[v=&quot;StateAbbreviation&quot;]&amp;/@#@&quot;BorderingStates&quot;#@v&amp;/@Interpreter[&quot;USState&quot;]@#|&quot;CA&quot;&quot;HI&quot;|&quot;AK&quot;&quot;WA&quot;/.&quot;MI&quot;&quot;MN&quot;|&quot;NY&quot;&quot;RI&quot;-&gt;0,a_ b_:&gt;a&lt;-&gt;b,3],#]&amp;

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TIO doesn't have data sets downloaded, so most of the footer is to ensure the code works as if they had been.
The BorderingStates properties differ from the given list of adjacencies in four ways: HI and AK do not border any other states, MI borders MN, and NY borders RI.
Interpreter[&quot;USStates&quot;]@#           (* get Entitys corresponding to abbreviations *)
#@&quot;BorderingStates&quot;                 (* for each state, get a list of bordering states, *)
#[v=&quot;StateAbbreviation&quot;]&amp;/@ % #@v&amp;  (* pair it (unordered) with each of those and convert back to abbreviations. *)
% /@ %%% |&quot;CA&quot;&quot;HI&quot;|&quot;AK&quot;&quot;WA&quot;         (* append CA-HI and AK-WA, *)
% /.&quot;MI&quot;&quot;MN&quot;|&quot;NY&quot;&quot;RI&quot;-&gt;0            (* discard MI-MN and NY-RI, *)
Cases[ % ,a_ b_:&gt;a&lt;-&gt;b,3]           (* then get all pairs and convert them to edges. *)
ConnectedGraphQ@Subgraph[ % ,#]&amp;    (* is the subgraph consisting of input states connected? *)



There's also GraphData[&quot;ContiguousUSAGraph&quot;], which is missing AK-WA, AZ-CO, CA-HI, and NM-UT edges. Unfortunately, the vertices are numbered in what seems to be an arbitrary order.