I've searched google, but have not found any method whereby I can use cryptsetup to encrypt an sd card.

Don't be quite so specific. Linux treats it the same as any other device so follow the instructions for encrypting a partition on a disk.

The only encryption I have done is with cryptsetup - encrypting an entire hdd.
"sudo cryptsetup luksFormat /dev/sdx --iter-time #"

Tried it with the micro-sd - didn't work.

$ sudo cryptsetup luksFormat /dev/sdd1
WARNING: Device /dev/sdd1 already contains a 'ext4' superblock signature.

WARNING!
========
This will overwrite data on /dev/sdd1 irrevocably.

Are you sure? (Type uppercase yes): yes
Operation aborted.

I've tried it a few ways and I keep getting error message: 'operation aborted'.

What didn't work? Did you actually use that exact syntax? There is no /dev/sdx. SD cards are often seen as /dev/mmcblk0 instead of /dev/sdc or whatever. What error message did you get? What does lsblk show for drives? As computersavvy said, one drive is like another for cryptsetup, as long as you give it the correct device name. And you need to encrypt a partition, not a full drive. There are many tutorials on using cryptsetup available on the internet. Perhaps reading one or more of them would give you more of an idea on how to go about it.

Don't you just hate it when people edit an answer while you're typing a response ?. At least it's now longer then one (short) sentence.
As suggested, let's see "lsblk -f" with the card plugged in.

Did you not notice that you were instructed to type uppercase YES? If you type yes, of course it aborts. It will abort if you type anything at all other than YES.

It says uppercase.

EDIT: Ooops, I had not seen #6.

FWIW, I just found out that I can run cryptsetup on the device itself, there's no need to create a partition first:
(or whatever device) (no partition number)
Kinda cool.

It's just a device node - you can also mkfs or pvcreate on one. Has a lot of advantages actually.

I'm far from expert on cryptsetup, and I've never tried to encrypt an entire drive. I generally need at least some unencrypted space, and I don't need a lot of encrypted space. I usually use Veracrypt for my encryption, and put both Linux and Windows portable versions on the drive, with an encrypted file container, so it can be used anywhere to access the encryted data. That makes more sense to me, but perhaps not everyone. For encrypting files on my HDD, though, it's somewhat cumbersome and a partition encrypted with cryptsetup is easier to use. So encrypting an entire drive isn't something I really care about. But my use case is not anyone else's, so it's good to know that an entire drive can be encrypted if desired. It still seems easier to just encrypt the partition, but perhaps not.

^ I just think it's a neat use case for having a completely encrypted removable medium to pop in/out.
And it saves a few extra commands when formatting.
File managers recognize the format and present you with a password dialog.

Yes, that's what I get from the encrypted partition on my SD card, which stays in the computer's slot. The file manager (Thunar in my case) displays it and presents a password dialog when I click on it. That's much more convenient than Veracrypt, but not as portable. Horses for courses, and all that. In the meantime, blooperx3 has not returned.

yes, it needed uppercase

appreciate the help)