The Omnipresent Recluse

Alternatively known as, "You probably weren't bitten by a recluse."

One of the most universally despised arthropods, the brown recluse, Loxosceles reclusa, is subject to many myths and rumors. It may come as a shock to you, but L. reclusa is not omnipresent, and its danger is greatly overstated.
Part of the problem with recluse spiders is that they are very reclusive (hence the name), so some data about them is speculation. Some speculation and theories are okay in the field of arachnology, but when they become rumors and start to harm the spider, they are a problem. The brown recluse is actually very docile, and it can't even bite humans unless it is physically pushed into your skin. Ergo, be careful when sticking your hands in cracks, but otherwise, you're fine.

You probably won't get bitten if you handle an L. reclusa, but you should probably not do so anyway, just to be safe.

Another myth about this spider is the power of its venom. It does have necrotic venom, meaning that untreated, it will dissolve tissue and cause lesions. However, the spider very rarely uses the full power of its venom, and if you notice it biting you, you can get to a doctor to have it treated. 

"But what if I don't see it biting me?" You probably weren't bitten by a spider if you don't see anything and then wake up the next day with something that looks like a spider bite. Even the lesions caused by a brown recluse bite can also be caused by other conditions (that still need to be treated). If you were bitten by a spider, but didn't see what type of spider--this could happen if you stick your hand in dirty laundry and accidentally get too close to an arachnid--it's very hard to accurately verify what type of spider bit you. So just be careful when you put your hands in cracks, and try not to push recluses into your hands.

Due mostly to misidentification, people often think they have seen a recluse when they have not. This chart shows the range of all the Loxosceles species in the United States.

If you have seen a recluse somewhere else, you probably haven't. It is possible that recluses could exist in tiny pockets elsewhere in the United States, but you should not assume so unless your spider has been positively identified as a recluse by the entomological and arachnological communities. That means your friend on the phone can't identify your spider as a recluse. And it's very hard for recluse populations to be established outside of these ranges because they need very specific habitat conditions that cannot be filled by locations outside of their range. 

The misidentification of other spiders as recluse spiders causes many unnecessary deaths as well, and this goes hand-in-hand with the range being blown out of proportion by lots of people. I cannot stress this enough: NOT ALL BROWN SPIDERS ARE RECLUSES. If you live outside of this range, the brown spider you've seen is not a recluse, Look at these common spiders that are misguidedly attributed as recluses: 

Not dangerous - Nursery Web Spider

Not dangerous - Carolina Wolf Spider

Not dangerous - Rabid Wolf Spider (ignore the scary name)

Not even a spider! Also not dangerous, but they can give a bit of a painful bite - Camel Spider (still not a spider)

These are not as dangerous as recluses, but their bites may cause necrotic wounds if untreated. Leave them alone and you'll be fine - Yellow Sac Spider

These may have the potential to create necrotic wounds and should not be messed with, but they are not recluses. There is much debate over the power of its venom, but it is currently not thought to be dangerous - Hobo Spider

Supposedly more dangerous than the brown recluse, although there are no formal records of a bite. These do not live in the US. They are recluses related to the brown recluse - Chilean Recluse (Loxosceles laeta)

This is a brown recluse. They can be identified by their 6 eyes and the violin on their "head." Do not identify them based on just one of those, and always ask for input from arachnid enthusiasts or scientists. The page "Insect Identification" on Facebook is great for this.