How did an Arizona Coral Snake get north of Chicago?

I was just finishing up a nice salad, colorful, mixed greens, half an avocado, Roma tomato slices and some diluted-with-water Western dressing, the last of the bottle. Out of the corner of my eye I saw movement. There on the floor and halfway up the glass front of my fireplace was a snake. It didn't move much, and it had bands of color that made it pretty and I came closer for another look. My snake didn't move, there was little kink in it, about five inches from its head, and the rest was strait out glued to the glass, then draped over the hearth and onto the floor.

This needs to be outside, I thought, and went to the kitchen, retrieved a pair of kitchen tongs and came back to pick it up. Not a good idea. I got hold of it and it came alive, soon all of it was back on the floor and heading for the floor grate that's the cold air return for the furnace. In less than a half minute it was entirely out of sight.

I called my neighbor, my go-to guy for most of my homeowner problems. I described my snake: red, black, white, nice even distribution of color, each color the same size as the next. About 18 inches long. Black head, black tail. If I didn't know better I'd say I had a coral snake. Probably something that only LOOKS like a coral snake because this is not the southwest.

My neighbor came over and we moved the electric fireplace and opened the floor grate. He spread heavy plastic film over the opening and was about to replace the grate when he said "there's your snake!" I was so glad someone else was seeing this because by now I felt I'd only imagined a coral snake in my living room. He removed the plastic and we both watched my snake retreat to a darker place in the duct. Back went the plastic, the grate, the fireplace. Stay down there!

This morning I called two furnace places that do duct cleaning. One of them I'd had cleaned the furnace ducts when I first bought this house. Having asthma in a house that was built in 1840, I needed reassurance that there was nothing dangerous in my air.

Alas this is now Good Friday and nobody will come out until Monday. We'll see.

Online, I ask lots of questions, look at all the pictures of snakes, find out I may have one that's very dangerous. The bite isn't so painful but the neurotoxin in the snake's venom will start to work shutting things down until death occurs in about an hour. Now I'm glad I didn't pick it up and have it bite me.

So, the question remains. How did an Arizona Coral Snake get north of Chicago?

Update - Friday 6 PM My expensive snake. Heating company came out (I'd called two, one didn't return my call) and looked around with a fiber optic camera and didn't find the snake. $79.00. They called Animal Control who came out an hour later and set glue-board traps and will be here tomorrow to check them. $175.00 plus $20.00 trip charge for every time they come and haven't gotten the snake yet. I felt even more apprehensive when they threw out the plastic covering to the vent. The glue traps around it on the floor are in addition to the ones they put inside the vent and down at the other end in the basement. When it's finally removed, another $400.00 for duct cleaning.

Update - Saturday 9 PM Animal control guy was here at 6 AM. I'd been up since 3. He checks upstairs and downstairs glue traps, no trap had moved. I've been walking around all day with a flashlight and look in there a lot. Baked a pie to keep warm. Made lots of coffee to keep warm. I'm not supposed to use the furnace. I don't know if that means they took the furnace apart. They seemed to think having the snake in the furnace would not be good. I told him not to come tomorrow, it's Easter Sunday. He said, "You sure? Well okay, I have a 4 yr old and it is Easter."

Have a list of new questions - can we lure it to the glue traps with maybe a hot dog? Actually the only meat I have in the house is some ham for sandwiches, and some frozen fish. Can we use smoke in the duct to make it move toward the glue traps. Can we end the search if we haven't found it in a week? What's the next step?

Called brother-in-law in Arizona. Maybe they have those snakes-in-the-house problems too. Well, no, but be careful. Keep a 5-gallon bucket handy. Wear sturdy shoes. Have some heavy leather gloves handy.

Anyone else got advice about snakes in a house? Dangerous ones?