Bathing has undergone a lot of changes throughout history and really depends on which region we're talking about. Americans bathing habits are different from most Europeans, for example. Also, "bathing" by definition involves submerging the body in water, so showering does not count under that definition as it was normally used. Washing daily in one way or another has been common practice since around the 17th century for most European-based societies. Washing the hands before meals as well.

As for baths themselves it comes down to the availability of running water, preferably hot, and the alteration of architectural structures to accommodate bath tubs. That's part of the reason Americans generally bathe more than their European counterparts, since at the beginning of the 20th century as the popularity of such practices took off America was building mostly new structures. Europe had to retrofit old buildings, which is far more difficult. There are some public bath houses and even attempts at public (but individual) showers in some areas, but that's still very inconvenient compared to today. Around the time of the 1930s-1950s we reach the point where the majority of buildings have private bathrooms and running water. It's also during the first half of the 20th century that you'll see the clean business explode with advertisements for soaps, shampoos, deodorants, and other "necessary" items for being healthy and non-offensive to others. So, a combination of access and commercial influence changed our washing habits into a daily shower or bath by mid-century in many places.