Throughout the century, Penang's cosmopolitan population, comprising Chinese, Malay, Indian, Peranakan, Eurasian, Thai and other ethnicities, grew rapidly in tandem with the economic prosperity. However, the population growth also led to social problems, such as inadequate sanitation and public health facilities, as well as rampant crime, with the latter culminating in the Penang Riots of 1867. Also in 1867, the Straits Settlements was made a British crown colony. Direct British rule meant better law enforcement, as the police force was beefed up and the secret societies that had previously plagued Penang were gradually outlawed. More investments were also made on health care and public transportation.