Sins are said to cry when they are gross, and manifest, and impudent, and such as highly provoke God to anger. He names only these two cities, as being the most eminent in state, and exemplary in wickedness; but under them he includes the rest, as appears by the story.
Related Commentaries of Genesis 18:20
Genesis 18:20
20 And the LORD said, Because the cry of Sodom and Gomorrah is great, and because their sin is very grievous;