Urban crime is based largely on population, and represents ordinary sorts of street crime. The most common urban crime rackets are Protection, Prostitution, Drugs, general theft and stolen goods dealing (Larceny) and illegal Gambling - though others are possible.
As a general rule, any single urban racket earns an annual income in firebirds of (0.05 x Population), and a single racketeer can't serve more than about 5000 people. The rate (by default 0.05) a racket earns is variable and set by staff, but it can be increased ICly by engaging in more aggressive efforts to push the racket. To do so, the racket's controller must first lay out some cash to cover expansion - 1 fb for every 50 people in the territory the racket covers - and then make a successful Wits+Streetwise roll. If the roll is successful, the annual percentage increases by 0.01. This can only be done once every few months, and can increase a racket's income to a maximum of 0.10.
Starting a new racket requires a similar investment, though the costs are higher. A new racket requires the expenditure of 1 fb per 25 people in the territory, and the new racket begins at a percentage equal to the VPs on the Streetwise roll, maxing out at 6 VPs.
Note: For ease, staff often ignores the 'racket' level of criminal income when dealing with smaller cities or areas far away from Vargo City. Instead, staff assigns income to the 'crew' that controls the city and assumes an appropriate number of associates under the crew's captain. The income of a crew off a city is generalized to ten percent, or (0.1 x Population). Increasing crew income requires the expenditure of 1 fb per 25 people in the territory, and establishing a crew in a city requires 1 fb per 10 people in the territory. VPs on 'establishing' rolls for crews are doubled, to a maximum of 12 VPs. Note that this investment assumes there are smaller, matching investments from associates under the crew's aegis.
Effects of Urban Crime
Crime is not without consequences. There's a certain assumed level of crime present in any city, but it is usually below the 'expected' level for a criminal enterprise to operate. For ease, the effects of crime on cities are tracked at the 'crew' level and based off the net income earned by all the crew chiefs in urban areas under a faction's control.
Essentially, every city can absorb a crew chief income equal to about eight percent of its population - and for every percent above eight, the city's controller takes a one percent loss to income. Particularly high crime may also incur a popularity cost, though it isn't mechanical. This income loss applies all the way up the feudal ladder - if a city is ruled by a baronet, the baronet sees a one percent loss, the baronet's baron sees a one percent loss and the baronet's baron's viscount sees a one percent loss. This represents the importance of cities as centers for regional trade - crime in cities has far-reaching effects on the surrounding regions.
If a larger fief contains several cities, the incomes of the various crews are added together and compared to the total urban population to determine the economic effect.
Urban Crime Example
If the city of Seren (pop. 10,000) has two crew chiefs each earning 500 fb, the controller of the city of Seren sees a 2% decrease in income due to crime - 1000 is 10% of 10,000, or 2% over the 8% Seren can absorb. If Seren is the only city this person controls, that's the decrease in their income - however, Seren is controlled by the Governor of Neuvaire, who also controls Siolta and Kenealy.
The crew in Siolta (pop. 5000) makes 450 fb/yr, just a little bit below 'standard' for a crew captain, but in Kenealy (pop. 5000) there has been an aggressive anti-crime effort and so the crew chief in Kenealy makes only 350 fb/yr. Thus, the Governor of Neuvaire - whose urban population is 20,000 - sees only a 1% increase in income, as the decreased crime elsewhere helps even out the higher crime in Seren.