In an 8 quart or larger stock pot, simmer the tart cherries and sugar over medium to medium high heat for one hour, stirring every 10 minutes.
Monitor the temperature of the jam. It will thicken and be ready for canning once the temperature reaches 220℉.
Wash the jars, lids, and bands in hot soapy water.
Fill the water bath canner and bring to a boil.
Using a food funnel, fill each jar, leaving 1/2 inch head space.
Run the bubble popper through to remove any air.
With a clean paper towel, wipe each rim of the jars clean.
Place the lids on the jars and tighten the bands only finger tight.
Using the jar lifter, place the jars into the boiling water bath.
Place the lid on top of the water bath and process for 10 minutes.
After the jam has processed, remove with the jar lifter onto a towel lined wooden cutting board and allow to cool. After cooling for 24 hours, label with the date and name and store in a cool dark place for up to 1 year.
Any jars that did not seal properly should be refrigerated and used first.