Yes, lead poisoning could really be a cause of violent crime

[happyslug]

96. Purchased of cars were concentrated in the Rural and Suburban areas prior to WWII

And during WWII, the actual number of motor vehicles DECLINED, as many former users of horses return to horses for the duration (The most noted were Milkmen).

AS to your picture of New York City in 1930 see the following quote of New York City TODAY:

New York is the only city in the United States where over half of all households do not own a car (Manhattan's non-ownership is even higher - around 75%; nationally, the rate is 8%).

Around 48% of New Yorkers own cars, yet fewer than 30% use them to commute to work, most finding public transportation cheaper and more convenient for that purpose,

http://en.wikipedia.org/wiki/Transportation_in_New_York_City#cite_note-2001summary-6

Walk and bicycle modes of travel account for 21% of all modes for trips in the city; nationally the rate for metro regions is about 8%

http://en.wikipedia.org/wiki/Transportation_in_New_York_City#cite_note-2001summary-6
http://nhts.ornl.gov/2001/pub/STT.pdf
http://www.census.gov/prod/2011pubs/acs-15.pdf

In 1930 the Car ownership rate in New York City was even lower. Today, 2013, over 54% of the people of New York use Public Transit to get to work, an additional 21% walk or ride a bike to work, for a total of 75%. The remaining 25% include not only people who drive, but people who fly, take a boat, or take a train to NYC to work.

In the 1920s GM did a study and found that the largest prospective area for growth in Auto usage was Rural America. Grain prices were up due to the fact the US Grain producers #1 competitor, Russia and the Ukraine, were out of the market due to turning Communist (More due to a refusal of other European countries to trade with them then anything else, this was reversed in 1927 when Stalin decided to dump grain onto the world market to pay for his first Five Year plan, but in most of the 20s Rural America was booming).

THe second largest group were Upper Middle Class Urban dwellers, who were also the first to move to the Suburbs, thus while most Working Class stiffs still walked to work from 1920 to 1946, managers and other professionals started to move out to the Suburbs AND use their automobiles to commute to work. Thus your picture proves nothing.

Most people in Urban Area were working class, not the poor, and not the 10% of the population generally considered "Upper Middle Class" (as that term is used today, the term "Middle Class" was used for them till the 1960s when it was decided that unions had moved the Working Class to Middle Class standards and with that change the term Middle Class started to include what use to be called Working Class). It was this group that started to buy cars as early as 1905, and continue to be the main source of car owners till after WWII in urban areas. Most urban areas, prior to the end of WWII mimicked New York City, it is only with the embrace of the automobile did the modern auto dominated city developed.

As to the 200 Motor Vehicles per 1000 people, remember that included trucks. In the 1920s and 1930s most cities pushed for trucks to replace horses, so the city did not have to clean up after the horses. Many of the motor vehicles purchased during the 1920s and 1930s in urban areas where such local delivery trucks. In my home city of Pittsburgh, the Streetcar system had to end its own fright hauling business in 1940 due to the fact so many businesses had adopted trucks to haul goods around that they no longer saw the Streetcar system as a fast alternative (it had been when the horse was use to haul goods). This demand for trucks, and the subsequent flexibility trucks provided, did in a number of Inter-Urban Streetcar systems. Interurbans tended to be more rural then urban and depended not only on passenger service, but freight service. For example the City of Hershey Streetcar system failed when Hershey switched from having farmers haul their milk to the Streetcar stop and instead had trucks pick up the milk directly from the farmers. THis mid 1920 change, killed off a income stream for that interurban Streetcar and forced it to close down.

Just a comment that 200 motor vehicles per 1000 people included trucks and a lot of vehicles in rural areas. These Rural vehicle, when they burned leaded gasoline, would have the effect minimize by the fact on a per mile basis, the vehicle count was low. Urban areas, would see a concentration of lead as more and more people drove to work just based on the number of vehicle in a relatively much smaller area.

I have found that most people living today can not even image living in a society without access to an automobile, yet that was the norm as late as 1945 in urban areas. I have found people refusing to accept that people can survive without cars but that was the norm for most people's great grand parents.