The wall is made of thin oak planks that her son made. He has a sawmill and sliced up the trunk of a dead oak tree.
Jasper Junction, and some of the things she was selling there are in her windows.
Below you can see the view from her window as she looks north on McKinley. If a truck failed to make the curve on McKinley, it could end up in her shop. (The guard rails would probably stop it.)