Well, I've asked this question of an entomologist on another site but the person I asked wasn't convinced that this is a mosquito of the Culicidae Psorophora family because of it's size and I'm not convinced that it's a crane fly. To me it seems that it is a mosquito because of it's proboscis and from what I've read and after comparing pictures with how this mosquito looks and the fact that we've had heavy rain lately and a couple flash flood scares. I think it may be Culicidae Psorophora Ferox but I'm not entirely sure. I was worried initially because of it's size and the fact that I had never seen a mosquito like it. I was worried that it might be carrying something. After having read some I've become more worried and inclined to not let it go. From what I've read they're known to carry some kind of arbovirus or something. I'm not entirely sure.

Here is the mosquito I have: http://i.imgur.com/tNAWh.jpg

Here is the mosquito I think it is: http://www.pbase.com/tmurray74/image/33422314

And here's where I've read stuff about the mosquito I think it is: http://wrbu.si.edu/generapages/psorophora.htm

ANY mosquito 'carries something' like west nile virus, how devastating can that be?? ;it doesn't have to be a large one. Use a lot of bug spray.

People die from west nile virus for heavens sake, and that comes from a very small mosquito.

Okay I looked at your pics, that is a dragon fly.

A "dragonfly" is a member of the Order Odonata. THAT IS NOT A DRAGONFLY.

It does look like a mosquito. Identification to species level is the purview of an expert. You might be able to get a species ID from your local vector (mosquito) control district, environmental health dept, or agriculture dept.

"Letting it go" will not really have any impact on the prevalence of disease in your area.

Culicidae is the family of mosquitoes. Psorophora is a genus name of some mosquitoes. There are other genera of mosquitoes, like Anopheles and Culex. Many mosquito species are carriers of devastating diseases.

I took another look at your mosquito picture. That is a big mosquito. I searched "large mosquito" and found this interesting website: Gallinipper mosquitoes are here (http://www.annarbor.com/news/gallinipper-mosquitoes-are-here-big-and-biting/#.UGzQQE20_kg)

... would hate it if they nipped my galli.

Crane flies do not have the piercing mouthparts that your picture shows.

Also, found this website about elephant mosquitoes (Toxorhynchites sp.) (http://www.dnr.sc.gov/cwcs/pdf/Predmosquit.pdf) This looks very much like what you have.