Remove 2 Tbsp. zest and squeeze 1/2 cup juice from lemons. In a 6- to 8-quart heavy pot combine sugar, crushed berries, and lemon zest and juice. Bring to boiling over medium heat, stirring constantly. Boil gently, uncovered, 25 to 30 minutes or until mixture sheets off a metal spoon and reaches 220 degrees F, stirring frequently. Whisk in cinnamon until thoroughly combined.
Ladle hot jam into hot, sterilized half-pint canning jars, leaving a 1/4-inch headspace. Wipe jar rims; adjust lids and screw bands.
Process filled jars in a boiling-water canner 5 minutes (start timing when water returns to boiling). Remove jars from canner; cool on wire racks.