Applied for US Passport Card, routine service. I had to submit my (still valid) passport with the application.
4/17/19 - mailed application via priority mail
4/20/19 - application arrived at facility
4/22/19 - check cashed
4/23/19 - application showed up in online system
5/22/19 - email received saying that passport card has been printed, will be mailed priority mail, and should be expected on or about 5/28
5/23/19 - Two more emails saying that the passport would be received on or around 6/1

I applied for the passport card so that I could visit Canada while I submit my actual passport for a visa application (applying for a long-term work visa for Switzerland). Was planning on starting the road trip on June 3rd, more than 6 weeks after the passport card application was received at the facility, which I assumed would be fine, but was starting to get nervous at 4.5 weeks, since they don't mail passport cards or your old passport back via priority mail, and wondering if I should call and expedite. Will probably wait another week I guess.

Update: I called the passport Info center, they acknowledged that it was still processing but it had only been 5 weeks and that if I wanted to I could pay $60 to expedite. I mentioned that I'm only 2 weeks away from when I need the card, and I wasn't sure if expediting would help. I also mentioned that I need the card by June 3rd, which is more than 6 weeks after the application was submitted (would be almost 7 weeks). She said that it is processing at a facility in Portsmouth, NH and that if I haven't heard anything by next week, to call again and they can arrange for me to make an appointment and potentially pick up my card at the facility (instead of waiting for it to come in the mail).

2nd update: Looks like the passport card is now printed, and should receive it by 5/28. This would mean total time door to door will be exactly 6 weeks. Will update when it is received.

edit: recieved 2 more emails, now the expected arrival is on or around 6/1. Just hope they don't push it out any farther. So what I have learned from this thread is that the processing time is highly variable, probably depends on the exact facility/state you are in, and routine processing can take up to 6 weeks not including mailing time.