Moscow had mud on the streets as late as early 2000s. Turns out, only with careful urban planning can you make sure that soil is undisturbed and any extra water

Moscow had mud on the streets as late as early 2000s. Turns out, only with careful urban planning can you make sure that soil is undisturbed and any extra water gets into drainage. By default you will get mud on the streets in wet climates (and dust in more arid ones).