Prepare the green beans: Rinse green beans thoroughly under cold running water. Trim the ends and remove any damaged beans. Cut or snap beans into pieces if needed to fit comfortably in the jars.
Prepare jars and canner: Wash jars, lids, and bands in hot, soapy water. Heat jars until hot, either by simmering in water or running through a dishwasher on a sanitize cycle. Keep jars hot until ready to fill. Prepare the pressure canner according to the manufacturer’s instructions.
Pack the jars: Tightly pack the prepared green beans into hot jars, leaving 1 inch of headspace. If using salt, add ½ teaspoon to each pint jar.
Add boiling water: Pour boiling water over the beans, maintaining 1 inch of headspace. Use a bubble remover or non-metallic spatula to remove trapped air bubbles. Adjust water level if needed.
Seal the jars: Wipe jar rims with a clean, damp cloth. Place lids on jars and screw bands on until fingertip-tight.
Process the jars: Place jars into the pressure canner following manufacturer instructions. Vent steam for 10 minutes, then bring the canner to pressure. Process pint jars at 10 pounds of pressure for 20 minutes, adjusting for altitude if necessary.
Cool and store: Turn off heat and allow the canner to depressurize naturally. Remove jars and place on a towel or rack. Let cool undisturbed for 12–24 hours. Check seals, remove bands, label, and store in a cool, dark place.