VS2017: C++: Iterating Through a const std::map<enum, string>: Link Error [duplicate]

I have a link error on the following code.

header file

    //we have a static class member std::map that I want to be read-only
    //the enums are numeric but not sequential
    typedef std::map<MyEnumType, std::string> MyStdMapType

    class MyClass { static const MyStdMapType myMap; }
    

source file

    //populate - static var outside of class
    const MyStdMapType MyClass::myMap = { {enumVal1, str1}, ... }
    

Then, later, I want to iterate through the map

      for (MyStdMapType::const_iterator iter = MyClass::myMap.begin(); iter != MyClass::myMap.end(); iter++)
      {
<stuff>
      }

The "for" line is giving a link error. If I comment the line out, it compiles!:

error LNK2001: unresolved external symbol "public: static class std::map<enum MyEnumType,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> >,struct std::less<enum MyEnumType>,class std::allocator<struct std::pair<enum MyEnumType const ,class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > > > > const MyClass::myMap" (?myMap@MyClass@@2V?$map@W4MyEnum@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@U?$less@W4MyEnum@@@3@V?$allocator@U?$pair@$$CBW4MyEnum@@V?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@std@@@3@@std@@B)