For example the 4th file is easily converted to this:
ClearAll[StateName]
StateName[in_] := Module[{data},
data = <|1 -> "AL", 2 -> "AK", 3 -> "AZ", 4 -> "AR", 5 -> "CA",
6 -> "CO", 7 -> "CT", 8 -> "DC", 9 -> "DE", 10 -> "FL",
11 -> "GA", 12 -> "HI", 13 -> "ID", 14 -> "IL", 15 -> "IN",
16 -> "IA", 17 -> "KS", 18 -> "KY", 19 -> "LA", 20 -> "ME",
21 -> "MD", 22 -> "MA", 23 -> "MI", 24 -> "MN", 25 -> "MS",
26 -> "MO", 27 -> "MT", 28 -> "NE", 29 -> "NV", 30 -> "NH",
31 -> "NJ", 32 -> "NM", 33 -> "NY", 34 -> "NC", 35 -> "ND",
36 -> "OH", 37 -> "OK", 38 -> "OR", 39 -> "PA", 40 -> "RI",
41 -> "SC", 42 -> "SD", 43 -> "TN", 44 -> "TX", 45 -> "UT",
46 -> "VT", 47 -> "VA", 48 -> "WA", 49 -> "WV", 50 -> "WI",
51 -> "WY"|>;
If[KeyExistsQ[data, in], data[in], "XX"]
]