For those of you who are new to the RGV, if you go to
http://www.rgvparks.com/ you will see that they will send you a free map of the area. It shows some of the RV parks and dealers, so it will help you get oriented. You will see that the RGV is really a collection of about a dozen towns and cities strung out along US83.
(I notice that it actually lists 46 parks, and I have heard that there are actually several hundred parks in the area. Some prominent ones that I know of are not listed, so this is just a sampler really.)