What cities have high crime rates?
Here is a list of US cities by crime rate. I can't find anythign specifically drug related; instead I'm going to focus at two statistics, overall violent crime rate, which is mostly robbery and assault, and murder.
There are four cities that are in the top 10 for both categories: Detroit, St. Louis, Memphis, and Baltimore.
What do those cities have in common?
(All stats from American Factfinder)
First is population decline. Since 1950, three out of the four cities have lost half their population...or more! Detroit dropped from 1,849,568 to 677,116; St. Louis from 856,796 to 315,685; Baltimore from 949,708 to 621,849. Memphis bucked this trend, but several other cities that score highly on the above list have lost a lot of population, as well: Buffalo (580,132->258,071), Cleveland (914,808->388,072), etc.
The second is poverty. Of those first four cities Detroit has 40.3% of its population below the poverty line; St. Louis 27.1%; Baltimore 23.7%; Memphis 27.1%. Those numbers are abnormally high. Compared to the states they are in, Michigan is 16.7%; Missouri is 15.6%;Maryland is 10%; and Tennessee is 17.6%. All those cities are 10% or more above the state average.
Third is concentrated poverty. Not all areas of those cities are super dangerous or decayed. Johns Hopkins in Baltimore is nice, as is CORTEX between Mid-town St. Louis and Forest Park. But, for example, Zip Code 63106 in St. Louis has a median income of \$13,000 with 60% below the poverty line. Zip code 38106 in Memphis has a median income of \$17,000 and poverty rate of 53%. In Baltimore, 21217 has an income of \$27,000 with 36% poverty; A mile away is the nice Roland Park district in zip code 21210 with income of $83,000 and a poverty rate of 9.6%.
Many of the most crime ridden cities in the US have followed a similar pattern.
First, automobiles became common and interstates were built connecting all these cities with their sparsely populated suburbs.
Second, industry in particular decamped from cramped and expensive cities to cheaper sites in the suburbs. Other industries just folded as a result of the gradual loss of manufacturing jobs in the US.
Third, the lower-middle class factory workers that packed these cities in 1950 started leaving. The ones who could afford it left for better pastures, leaving only the poorer behind. As customers left the city, small businesses went under; their owners left too stripping the middle classes of those cities.
Fourth, crime started ticking up in the worst neighborhoods. Therefore the rich isolated themselves in their rich people enclaves and left the rest of the city to rot.
Fifth, as the rest of the city rotted, there became basically no reason for the middle class to be there. The cities became divided between the richest people in the country, and the poorest. This dichotomy between rich and poor in the most successful cities in the US is obvious: Manhattan is the richest county in the country by per capita income; the Bronx is 2710th, around the 12th percentile.