Map Editor / Import different Level Objects?

Hi everyone,
i started to "play around" with the Map Editor, like placing Houses and changing the surroundings of it etc.
For now, i only use East Coast USA for it, since it is my Favorite.

Anyways, i´m getting along pretty good with the Editor, but it seems that there´re only East Coast Objects and Materials in the Editor, like the Houses, Ground Textures, Signs, and so on.
Is there any Way, i can import Objects / Textures from other Game Levels, like Utah, West Coast etc. into my Current Map, and use it there?

Thanks for your Help!