Prep beans. Rinse the green beans thoroughly in cold water. Trim the ends, and if desired, cut or snap the beans into pieces to fit your jars.
Clean jars. Wash and heat your canning jars, lids, and bands by boiling them for 10 minutes or using a dishwasher on the sanitize cycle. Keep jars hot until ready to use.
Fill jars. Tightly pack the green beans into the hot jars, leaving a 1-inch headspace at the top. If using, add 1/2 teaspoon of salt to each pint jar.
Add boiling water. Pour boiling water over the beans in the jars, maintaining the 1-inch headspace. Use a bubble freer or a non-metallic spatula to remove air bubbles by gently sliding it between the beans and the jar.
Seal jars. Wipe the rims of the jars with a clean, damp cloth. Place the lids on the jars, then screw on the bands until fingertip tight.
Process. Place the jars in your pressure canner, following the manufacturer's instructions. Process pint jars at 10 pounds of pressure for 20 minutes (adjust for altitude if necessary).
Cool and store. Turn off the heat and allow the canner to depressurize naturally. Carefully remove the jars using a jar lifter and let them cool on a towel or rack for 12-24 hours. Check the seals, then label and store the jars in a cool, dark place.