Wash tomatoes. Dip in boiling water 30–60 seconds or until skins split, then dip in cold water. Slip off skins, remove cores, trim bruised portions, and quarter.
Heat about one-sixth of the quarters quickly in a large pot, crushing them as they are added. Once boiling, gradually add the remaining quartered tomatoes while stirring constantly.
Boil gently 5 minutes after all tomatoes are added.
Add required bottled lemon juice or citric acid to each jar. Add salt if desired.
Fill hot jars immediately with crushed tomatoes, leaving 1/2-inch headspace.
Boiling-water process pints 35/40/45/50 minutes and quarts 45/50/55/60 minutes at 0–1,000/1,001–3,000/3,001–6,000/above 6,000 ft. Pressure-canning alternatives must follow the NCHFP table exactly; acidification is still required.