This is Texas, the year before, the formation of Llano County. The places colored Purple are unorganized counties. Notice how large Bexar  (abbrev - Bex) is, and without borders, here.

Here you see Llano is created but Mason is yet to be organized. So, the western border of Llano is open country.

Here, in 1858 Mason is created but Menard, McCullough, Kimble and others are still unorganized. but, the Territories of Young and Bexar District are created from the vacant lands.

These maps were supplied by Gold Bug Historic Maps & Software.

Visit their website at http://www.goldbug.com for historic map reproductions,
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Geographic Servers and other interesting sites.