provide greater efficiency by centralizing command and resources and to resolve jurisdictional problems, often in communities experiencing rapid population growth and urban sprawl, or in neighboring communities too small to afford individual police departments. Some county sheriff's departments, such as the Los Angeles County Sheriff's Department, are contracted to provide full police services to local cities within their counties. Likewise, in Florida, the Duval County Road Patrol and the Jacksonville Police Department consolidated in 1968 to form the "Office of the Sheriff - Jacksonville Police," commonly known as the Jacksonville Sheriff's Office, policing all of Duval County. Puerto Rico Police The Puerto Rico Police Department (PRPD) traces back to 1837, when Spanish governor Francisco Javier de Moreda y Prieto created La Guardia Civil de Puerto Rico (Puerto Rico Civil Guard) to protect the lives and property of Puerto Ricans who at the time were Spanish subjects, and provide police services to the entire island, even though many municipalities maintained their own police force. The United States invaded and took possession of Puerto Rico in July 1898 as a result of the Spanish–American War and has controlled the island as a US territory since then. The Insular Police of Puerto Rico was created on February 21, 1899, under the command of Colonel Frank Thacher (U.S. Marine officer during the Spanish–American War), with an authorized strength of 313 sworn officers. As of 2009, the PRPD had over 17,292 officers. Other There are other types of specialist law enforcement agency with varying jurisdictions. Most of these serve special-purpose districts and are known as special district police. In some states, they serve as little more than security police, but in states such as California, special district forces are composed of fully sworn police officers with statewide authority. These agencies can be transit police, school district police, campus police, airport police, harbor police, railroad police, park police or police detectives and animal control service responsible for protecting government property, such as the former Los Angeles General Services Police. Some agencies, such as the Port Authority of New York and New Jersey Police Department, have multi-state powers. There are also some private police agencies, such as the Parkchester Department of Public Safety and Co-op City Department of Public Safety. Police functions Textbooks and scholars have identified three primary police agency functions. The following is cited from The American System of Criminal Justice, by George F. Cole