Paragraph: The rank-size rule does not work for El Salvador. The estimated sizes for the cities are nowhere near where the actual sizes are. Their second largest city is Soyapango. The estimated size of this city was 140,935, the actual size of this city is 275,868. The rank-size rule is invalid in this country. Population: 6,156,670 Population density: 295.68 % Urban population: 67% % Urban population living in Slums: N/A Average % change in urban population: 1.0% % with improved urban sanitation: 75% % with improved urban water supply: 98%