The San Francisco Bay Area comprises nine northern California counties and contains four of the ten most expensive counties in the United States. Strong economic growth has created hundreds of thousands of new jobs, but coupled with severe restrictions on building new housing units, it has resulted in an extreme housing shortage which has driven rents to extremely high levels. The Sacramento Bee notes that large cities like San Francisco and Los Angeles both attribute their recent increases in homeless people to the housing shortage, with the result that homelessness in California overall has increased by 15% from 2015 to 2017. In September 2019, the Council of Economic Advisers released a report in which they stated that deregulation of the housing markets would reduce homelessness in some of the most constrained markets by estimates of 54% in San Francisco, 40 percent in Los Angeles, and 38 percent in San Diego, because rents would fall by 55 percent, 41 percent, and 39 percent respectively. In San Francisco, a minimum wage worker would have to work approximately 4.7 full-time jobs to be able to spend less than 30% of their income on renting a two-bedroom apartment. San Francisco has several thousand homeless people, despite extensive efforts by city government to address the issue. San Francisco's dense, compact development pattern, its comparative lack of vacant land (i.e., beneath freeways, alongside creeks), and its high volumes of pedestrians tend to limit homeless encampments to the city's sidewalks and thus more readily visible to the general public. This dramatically-larger prevalence of visible homelessness in the city, relative to other large US cities, is widely noted by visitors as well as residents. As of 2018, this had begun to impact the city's largest industry, tourism (a $9 billion industry), as one large doctors' group has decided to move their annual convention elsewhere after members' concerns about threatening behavior, mental illness, and assault on one of their board members. The number of the people in poverty in the San Francisco Bay Area grew from 573,333 (8.6%) in 2000 to 668,876 (9.7%) in 2006-2010. While poverty rates vary greatly across the SF Bay area, in 2015, the Silicon Valley Institute for Regional Studies published that the poverty rate was 11.3%, having a slight downward trend from 12%; however, it was still above the historical average rate of 9%. (en)