How to merge .tif files into one image

[SeanWineland]

I have a series of topographic maps by county that I am trying to merge together to use for a clip. I have tried using the mosaic to new raster function but the output gave me a merged image that is all jumbled up. The counties are not oriented properly (see attached images). I input the correct geographic coordinate system in the dialog window for mosaic to new raster function. So how do I fix it? It should look like the image where everything is aligned.

Any help would be greatly appreciated!

[SeanWineland]

I should add that these .tif files all had black borders around them that I tried to take away by just changing the symbology, but I realize this may not be enough for when i run the mosaic to new raster function.

[DanPatterson_Retired]

I would have a look at mosaic datasets as your starting point (esp that collar thing) then there are options to limit the extent (like clip) in a variety of ways.