She’s in the passport office downtown right now. Awaiting news.
Have her go to the Passport Agency office in Chicago. She’ll need to make a sameday appointment online
She’ll need to fill out an application for a replacement passport. USE BLACK INK. Any other color and they’ll make her do it again.
They can process the replacement passport same day.
Good luck
A ray of hope?! 
OH HAPPY DAY!!
Just got a text from my SiL. She said her new passport will be ready by one o’clock the latest, which gives her 2 1/2 hours to make the 45 minute trip to my apartment so that we can leave for the airport in plenty of time!
Thank all of you who contributed!! 
A definite plus to living in a major urban area! That’s awesome! Plenty of stress to go around…
Truth! I spent half the night tearing my place apart looking for it. I’m totally fried. Thank God I have a 3-day weekend to recover.
That’s great news!
I once lost my passport somewhere between Geneva and Frankfurt so I couldn’t get on the plane back to the US. We set up an appointment for the US Consolate the next day (it was Sunday when this happened) and resigned ourselves to spending a few extra days in Germany before we could go home.
After about 2 hours of scrambling, a guy from US Homeland Security found me waiting in the Lufthansa lounge. He confirmed my identity with my drivers license, pulled up an image of my passport on his phone, and said “Come with me.” We walked up to the gate, he got me on the plane, and we were flying to Boston just 2 1/2 hours after finding out my passport was missing.
Going through Immigration in Boston was another matter…
Any chance you can meet her downtown and take her directly to the airport? The way things have gone you might want to get to the airport really, really early, just because.
Now that she will get a replacement, the original should be found around 12:45…
Brian
I’d like that but she has her car with her. Got to get it back here. If, however, there is a delay, we can go to “Plan B”, which would be for her to leave her car in whatever garage it currently resides. I would load her luggage in my car, pick her up downtown, drive to the airport, come home, and get a ride back downtown to pick up her car. Ouch! Really don’t want to do all that.
AHHHHHHHHH! 
Only fifteen minutes ago, I asked my boss, “Now that she has a replacement, what is the “over-under” on how soon she will find the one she lost?”
Exactly what I was thinking. Thread must be updated when and where passport is found. 
That’s a promise. LOL
Jasmine (deep, heavy Austrian accent): “Come with me if you want to fly.”
Good news! She is at my apartment with her replacement passport, so there is no “Plan B” needed! Thank the good Lord for that! LOL
Glad to hear that! I was picturing the worst: She locates her lost passport which is now no longer valid (I’m pretty sure they invalidate the old one, even if not expired, the minute you submit the application to get a replacement) and the new one doesn’t arrive in time.
Don’t leave us hanging… Tell us the story!
Seriously, what are the procedures for an American citizen arriving from overseas without a passport?
.
.
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(This almost happened to me, and it was scary. I’m glad I didn’t have to find out .)
It actually wasn’t bad at all. We got to Immigration in Boston and spoke to the officers before we got in line. They looked at each other, sighed, and said “They’re supposed to call ahead when this happens.” They took me and my wife into the back office and we explained the situation. The next 30 minutes was spent just waiting, answering questions, and showing my drivers license while they trained a new officer in how to do the data entry for this type of thing. They gave me a piece of paper, and told us to go fetch our luggage and apply for a new passport. The whole thing probably added an hour to our return.
Is the US Consolate a special place that makes US travelers abroad feel better after they have problems? ;-D