I have been flying in a residential field for months now.  I have the VAS Crosshair and it has improved my distance by a little bit.

Is my distance barrier the wi-fi blasting out of my neighbors?  And power lines?

There’s no hills, mountains, large fields, etc near me... just trying to see what you guys have experienced.

I will soon start looking for other areas... who’s all flying in residential areas and how far are you going?

The RF noise of your flight site certainly contributes to the interference. Your vTx antenna, and it's placement has a lot to do with your signal quality. If you're flying a carbon framed quad, your quad will contribute to the interference. Not that you're doing long range flying, but if you observe the vTx antenna placement on LR quads, you can see that they distance the radiating element from the frame.

Yes, what you are talking about is what is called the noise floor.  Even things like powerlines as you mention can impact your signal and frequencies far outside what your VTX is running on will also affect your signal if the transmission is powerful enough. 

As an example, I fly out many miles where I fly with clear video.  But at my residence I get noticeable break up when I get near the neighbors houses.  

As GeeVee mentions and has been mentioned here many times, antenna placement is key.  You want the VTX antenna bulb well above the carbon frame and batteries, etc.