"U.S. bombing of Cambodia extended over the entire eastern one-half of the country and was especially intense in the heavily populated southeastern one-quarter of the country, including a wide ring surrounding the largest city of Phnom Penh. In large areas, according to maps of U.S. bombing sites, it appears that nearly every square mile of land was hit by bombs with roughly 500,000 tons of bombs dropped. [..]"
From https://en.wikipedia.org/wiki/Operation_Freedom_Deal#Cambodi...:
"U.S. bombing of Cambodia extended over the entire eastern one-half of the country and was especially intense in the heavily populated southeastern one-quarter of the country, including a wide ring surrounding the largest city of Phnom Penh. In large areas, according to maps of U.S. bombing sites, it appears that nearly every square mile of land was hit by bombs with roughly 500,000 tons of bombs dropped. [..]"