1919 SC 531 Precancellation?

Is this a pre-cancellation?

Yes, it is


Peter

but not SC 531

I must be the worst stamp cataloger in history, I don't get one thing right...

Yes you did. It IS a precancel!


Peter

I agree with chasa, your stamp is *not* a 531. And admittedly, your stamp can be a bit tricky to a beginner.. To help us help you through the process to arrive at the correct ID, it might be helpfulto know what online or printed resource(s) you are using to ID your stamps, and what choices you considered, etc. That way we can guide you to a better resource or through a process, which will result in faster and better IDs for you.

I have used this website https://stampsmarter.org/1847usa/wa...ankmain.html and I decided on 531 since the reverse did not seem flat plate to me... it looks very clean and smooth.

Additional information on IDing printing type can be found here
https://stampsmarter.org/learning/M...methods.html
Don

Excellent. Thanks.
I said your stamp was a "bit tricky". It is a perf 10 vertical, coil stamp, which is the link to follow on the stampsmarter page you posted. Coils (and precancels) were most often used by high volume uses, typically businesses. Many of them used affixing machines such as the one shown in this thread:
https://goscf.com/t/69080
The affixers often missed the perforations. Your stamp has the two natural straight edges of a coil at the top and bottom, and the knifing of the affixer at left/right which completely removed the perfs at left and left generous ones at right. So the imperforate left side is deceptive. It is consumer damage rather than a USPOD production trait.
All that said, it should lead you to 3 options to explore further:
443, flat plate. single line watermark.
452, rotary, single line watermark.
490, rotary, unwatermarked.

Very thankful!! Thanks to your instructions I have identified it as 490, there is no watermark!!