Wash potatoes by rinsing under cool water. Peel potatoes and remove any soft or dark spots. Rinse again. Potatoes that are 2 inches in diameter or smaller may be canned whole. Cut large potatoes into evenly sized cubes.
Put potatoes in a large saucepan and cover with water. Bring mixture to a boil. Once boil starts, boil for 10 minutes.
Pack hot potatoes into hot jars leaving 1-inch head space. Add 1/2 teaspoon salt per pint jar or 1 teaspoon per quart jar.
Ladle hot cooking liquid or boiling water over potatoes, leaving 1-inch head space. Remove bubbles and wipe clean the rims of the jars.
Center lid on the jar and adjust the band to fingertip-tight. Place jars on the rack in a pressure canner containing 2 inches of simmering (180 degrees) water.
Place lid on the canner and turn to a locked position. Adjust heat to medium-high. Vent steam 10 minutes. Put a weighted gauge on the vent. Bring pressure to 10 pounds (psi). Process pint jars 35 minutes; quarts 40 minutes.
Turn off heat; cool canner to zero pressure. After 5 minutes, remove the lid. Let jars cool 10 minutes. Remove jars from canner and place on a towel. Do not retighten bands if loose. Cool for 24 hours. Check seals. Remove rings, wipe jars, and store in a cool dark, and dry pantry.
If you are new to pressure canning, I suggest you head over to my post Learn How To Pressure Can. Pressure canning is a way to safely preserve low acid foods such as potatoes. The pressure canner is able to heat the food to a higher and constant temperature to kill botulism spores. Using a boiling water bath canner only kills botulism bacteria, but the spores can survive in low acid foods that are not heated above the boiling point for a specific length of time.