This is a single sided Porcelain Texaco Sign.  this sign is very old, it has the green T in the center, which they used in a couple of of different time periods but this one is from the mid 1930-mid 1960s,, because of he lighter color of the green in the T.  I would estimate this to be a 1940s sign, that's our opinion.  
 
It has chipped porcelain, fading, and wear, and a few areas that have been touched up by paint.  There are holes around the outside for mounting it.