The original seasoning was invented in the 1940's by an American-German immigrant named Gustav Brunn. Initially, it was intended only for use on crab meat (as there was plenty of it in the Chesapeake Bay area where Gustav lived!), but in the last decade or so, it's used in other food areas, such as poultry and salads.
Blend ingredients in a blender or spice grinder to a medium grind consistency. Combine all ingredients in an airtight container and shake well. Store in a cool, dry place.
I save the empty large spice containers and reuse them for my spice blends.
I've reduced the amount of salt and I use celery powder instead of celery seed. I also use cayenne pepper instead of red pepper flakes. If you are watching your salt intake, just omit the salt all together and or use a salt substitute.