I recently drove from Birmingham, Alabama to New Orleans, Louisiana.  Driving across the state of Mississippi, on a two lane freeway with sparse traffic, I saw what I immediately identified (in my novice opinion) as Hyenas walking along the side of the road...in the grassy/wooded areas off the side of the freeway.  I saw two of them travelling somewhat close to each other...and then many miles further down the road a spotted another of the same creature, and another miles down from that.

I couldn't believe my eyes.  I know nearly every breed of fox, dog, coyote...and this animal was not it.  The shape...looking somewhat hunchbacked, with a higher front half than the lower, walking with the neck and head curving downward...the ears being short and somewhat upright, but not like any fox...about the size of a German shepherd, short haired, and with a head shaped not quite like any dog or cat I have ever seen...it looked to me distinctly like a hyena.

I didn't try to get close to any of them, and I didn't think it remarkable...since there were a few out there, I thought this must be natural to the region.  Then when I got back to my hometown of Detroit, Michigan, I was at a dinner party at a riverside club, and one of the gentlemen at my table remarked that he saw what he thought to be a hyena roaming the private drive leading up to the club, just near the waterfront (in 20 degree winter weather).  

Do Hyenas exist in North America's Wilderness?  Is this a creature that resembles the Hyena...a relative?

Well there certainly shouldn't be, but that doesn't necessarily mean they are not out there. There are various medium and big cats living in the wild that have escaped or been released from collections in the UK for example (including puma and lynx) and we have at least one breeding population of escaped wallabys and Chinese deer too.

It's improbable but not impossible that some hyena have got out and are roaming wild in your area. You seem to know the local canids and what a hyena looks like. What we really need is a photo. Still, you could check in with the local wildlife services or even the police to see if there are reports of hyena or any registed escapees.

I would add that sometimes an animal's gait and posture can be misleading as a form of identification. Gait and posture can be influenced by injury, the surface being walked on and by overall condition. Pregnancy will also change the gait, posture and outline shape of a canid, making it hard to identify from a distance. I have certainly seen pregnant dogs from a distance and done a double-take because they looked superficially like hyaena (back legs look short because of the distended belly, head lowered, shoulders look hunched, fore and hind limb activity look disproportionate in gait, etc.).

Given the time of year I would expect that some female coyotes would be pregnant enough to start showing a little by now (and plenty of domestic and feral dogs), but not so far gone as to be obviously pregnant (if you get my drift). It would be interesting to see if there is an increase in sightings of hyaena-like animals between February and April each year...

That said, I agree with Dave - we can't be sure unless we see a photo and there is certainly the possibly of escapee hyaena!