There are two big, overarching changes, from which flow a whole other range of smaller changes. These changes are well underway in Britain from the late 18th century, which is not surprising as Britain was a lot more urbanized that the rest of Europe. But, the rest of continent--and indeed much of world at slightly varying times--follows by the turn of the 20th century.

The two major changes are rapid and unprecedented growth in both people and physical size, and the adoption of fossil fuel-powered economies. These two changes in cities are themselves well intertwined with the overall development of capitalism across Europe. Beginning in Britain in the early 19th century, and with the continent following for the rest of the century, the various mercantilist and even older feudal structures of European economy and society were dismantled. This meant, for example, the emancipation of serfs. They were effectively free in many areas from later medieval and early modern times, but a lot of the older rules remained on the books, and were eliminated at this point: serfdom was officially abolished in France in 1789; Prussia in 1807, other German states after that; Russia passed legislation on this in 1861. What these legal changes did, among other things, was "liberalize" the agricultural economies of Europe. Feudal (or whatever we want to call them) agrarian societies tended to place the most value on parcels of land; the labor on it was attached to it, and productivity of that land was a function of the serfs' or peasants' rights. They would work in certain customary ways that were designed to maximize stability of the overall rural society, and not profit or productivity. Land holdings might be periodically redistributed among the local cultivators, for example, to ensure equal access to enough land; labor was often communally organized; there was relatively little innovation or capital investment, as cultivators were risk-averse, so they tended to continue working the land as they had always done. There were also frequently a lot rules governing the trade in food, typically designed to keep prices low by outlawing hoarding, ensuring market access to everyone, preventing exports and/or imports depending on prices. In Britain, there was the Assize of Bread, which tied the price of a loaf of bread to the price of a quarter (an Imperial measurement) of grain. All of these things meant that cities were fairly limited in size, if for no other reason than that there was not a particularly large surplus of food to feed urban populations.

The official emancipation of serfs, and the less "official" spread of market relationships to the countryside altered this. It was well underway in some parts of Western Europe in the 16th and 17th centuries, but reached its full extent and became far more common across the continent through the 19th century. Removing those older regulations on the economy meant liberalizing the markets for land, labor, and capital. In so doing, workers became wage workers, and the key to economic growth became improving labor productivity. This encouraged greater capital investments in agriculture and greater specialization in farming. The rural workforce of Europe went from locally-oriented production and consumption with fairly low productivity to much more productive, capital-intensive, commercial agriculture. The farmers of Europe shifted from feeding themselves and their local areas with a wide range of foodstuffs (to spread the risk) to producing commodity crops for a continent-wide market in agricultural produce. They produced a great deal more, and cities could grow. As I noted, this process was well underway in Britain as early as the late 17th century, but became a European-wide system by the end of the 19th century: the opening of the Ukrainian wheat fields with railways and irrigation systems, for example, allowed consumers in France or Germany to eat wheat from Ukraine.

So, with the increased productivity of European agriculture, it is possible--and even desirable--for cities to grow, and they do. The urbanization of Britain, France, Germany, and other European nations is pretty remarkable. London is about 1 million in 1800, and 6.5 million by 1900; Paris goes from about 500k in 1800, to pushing 3 million by 1900; Berlin is under 200k in 1800, and nearly 2 million by 1900. Other parts of Europe follow. Much of this population is peasants and rural laborers displaced by the commercialization of agriculture, who came to cities looking for work. There's some debate as to why they came; wages were higher in cities, but there's also a case to be made that the quality of life declined significantly for those who did enter cities.

European cities also industrialized at this same time. For me, and I think for most environmental historians, the crucial change in industrialization is the the much greater exploitation of fossil fuels. In the 19th century, this meant primarily coal. Coal opened up a vast stream of potential energy for human exploitation: as raw heat, it was used for glass, ceramics, bricks, dying, brewing, and a whole range of other industries. In somewhat more refined form as coke, it was used for metallurgy. And, with steam engines heat could be converted into motion, making possible some automation in factories and dramatically reducing transportation costs through railways and steamships (although sail remained the dominant mode of water transport through the 19th c.). The reduction of transportation costs, and the emphasis on labor productivity through capital investment (basically large-scale factories), meant that the European (and ultimately the global) economy was reoriented around urban concentrations of highly productive labor based on fossil fuels. It made far more sense, for example, to mine coal or ore, grow grain, raise animals, cut down forests, and so on, where ever those items could be obtained, but to do the actual processing of those material in the cities. A great example from my own research is grain milling. In the 18th century, the British countryside was filled with mills, usually windmills. They ground the grain that was grown in their immediate vicinity for basically local consumption. As such, windmills in greater concentration in grain-growing districts and were situated according to local environmental conditions: on hills, for example, where the wind would be better. In the 19th century, however, the commercialization of the grain trade and the shift to steam-engines as power sources meant that it made more sense to put mills in the cities, especially in port cities where there was the greatest access to the raw materials: grain shipments from local and regional (and later global) sources, and coal. So, the country mills largely disappeared, and were replaced by much larger mills in Liverpool, London, Bristol, Glasgow, and Hull. Those five cities accounted for something like 90% of the milling capacity in Britain by the end of the century. You can find the same patterns with things like textile manufacturing, metalworking, later chemical industries and and more elaborate manufacturing.

So, cities are bigger and they run on fossil fuels. How does this change the forms of the cities themselves? These are the "smaller" changes that I referred to at the beginning. We could spend all day on this, but I'm going to outline three things that I think are typical: water, air, and buildings. In terms of water, the cities of early modern Europe were generally small enough that there was sufficient supply of water for drinking, industrial use, and to carry away waste products. With the rapid growth in populations, those water supplies were totally overwhelmed. The result was filth and disease: cholera, a water-borne disease, was absolutely rampant in cities in the 19th century. Rivers in industrial centers like Manchester and London were notorious for their foul odors and disgusting colors. The Rhine became, in the words of the historian Marc Cioc, nothing but "an industrial sewer" for the German cities springing up in the Ruhr Valley. In dry summers, "Great Stinks" occurred, in which the levels of rivers dropped so much that the human and industrial waste in them totally overwhelmed the flow, producing noxious smells even worse than usual, with attendance panics about health. Recall that for much of the 19th century, the dominant theory of disease was miasmatic, meaning that physicians and the general public attributed many instances of ill-health to the stenches producing by decomposing matter. So, when Paris was hit by a "Great Stink" in the 1870s, it was not only disgusting but also seen as a public health threat. The solution to these kinds of problems was ultimately to construct a great deal more infrastructure. The London Embankment was constructed in the 1860s, and it houses the mainline of the original sewer. Other cities followed suit, building massive sewer systems that would dump waste further downriver. Cities also reached further out into their hinterlands for fresh water supplies, building aqueducts and reservoirs to tap into distant and hopefully cleaner lakes and rivers, and to store the water until it was needed by urban consumers.

[Character limit. Lame.]