Tijuana is the largest city of both Baja California State and the Baja California Peninsula. It is part of the San Diego–Tijuana transborder urban agglomeration and the larger Southern California megalopolis. As the 6th-largest city in Mexico and center of the 6th-largest metro area in Mexico, Tijuana exerts a strong influence in education and politics – across Mexico, in transportation, culture and art – across all three Californias (the U.S. state of California, Baja California and Baja California Sur), and in manufacturing and as a migration hub – across the North American continent. Currently one of the fastest-growing metropolitan areas in Mexico, the city of Tijuana had a population of 1,641,570. The city is the most visited border city in the world; sharing a border of about with its sister city San Diego. More than fifty million people cross the border between these two cities every year. This metropolitan crossing makes the San Ysidro Port of Entry the fourth busiest land-border crossing in the world. It is estimated that the two border crossing stations between the cities proper of San Diego and Tijuana account for 300,000 daily border crossings alone. Tijuana is the 45th largest city in the Americas and is the westernmost city in Mexico. According to the 2015 census, the Tijuana metropolitan area was the fifth-largest in Mexico, with a population of 1,840,710, making it the third-largest metropolitan area in the former Californias region, 19th largest metropolitan area in the Americas, and the largest bi-national conurbation that is shared between US and Mexico. Tijuana is becoming more suburbanized like San Diego. Tijuana traces its modern history to the arrival of Spanish explorers in the 16th century who were mapping the coast of the Californias. As the American occupation of the Mexican capital ended with the Treaty of Guadalupe Hidalgo, Tijuana's new international position on the border gave rise to a new economic and political structure. The city was founded on July 11, 1889 as urban development began. Often known by its supposed initials, T.J., and nicknamed Gateway to Mexico, the city has historically served as a tourist center dating back to the 1880s.

Temecula is a city in southwestern Riverside County, California, United States. The city is a tourist and resort destination, with the Temecula Valley Wine Country, Old Town Temecula, the Temecula Valley Polo Club, the Temecula Valley Balloon & Wine Festival, the Temecula Valley International Film Festival, championship golf courses, and resort accommodations for tourists which contribute to the city's economic profile. Although geographically located much closer to San Diego County as well as San Diego City proper, Temecula is considered part of the Greater Los Angeles area. The city of Temecula, forming the southwestern anchor of the Inland Empire region, is approximately north of downtown San Diego and southeast of downtown Los Angeles. Temecula is bordered by the city of Murrieta to the north and the Pechanga Indian Reservation and San Diego County to the south. Temecula had a population of 100,097 during the 2010 census and an estimated population of 114,761 as of July 1, 2019. It was incorporated on December 1, 1989.

Los Angeles (Los Ángeles; ), officially the City of Los Angeles and often known by its initials L.A. (or simply LA), is the largest city in the U.S. state of California. With an estimated population of nearly four million people, it is the country's second most populous city (after New York City) and the third most populous city in North America (after Mexico City and New York City). Los Angeles is known for its Mediterranean climate, ethnic diversity, Hollywood entertainment industry, and its sprawling metropolis. Los Angeles lies in a basin in Southern California, adjacent to the Pacific Ocean, with mountains as high as and deserts. The city, which covers about is the seat of Los Angeles County, the most populous county in the United States. The Los Angeles metropolitan area (MSA) is home to 13.1 million people, making it the second-largest metropolitan area in the nation after New York. Greater Los Angeles includes metro Los Angeles as well as the Inland Empire and Ventura County. It is the second most populous U.S. combined statistical area, also after New York, with a 2015 estimate of 18.7 million people. Home to the Chumash and Tongva, Los Angeles was claimed by Juan Rodríguez Cabrillo for Spain in 1542. The city was founded on September 4, 1781, by Spanish governor Felipe de Neve. It became a part of Mexico in 1821 following the Mexican War of Independence. In 1848, at the end of the Mexican–American War, Los Angeles and the rest of California were purchased as part of the Treaty of Guadalupe Hidalgo, and thus became part of the United States. Los Angeles was incorporated as a municipality on April 4, 1850, five months before California achieved statehood. The discovery of oil in the 1890s brought rapid growth to the city. The city was further expanded with the completion of the Los Angeles Aqueduct in 1913, which delivers water from Eastern California. Los Angeles has a diverse economy and hosts businesses in a broad range of professional and cultural fields. It also has the busiest container port in the entire Americas. A global city, it has been ranked 6th in the Global Cities Index and 9th in the Global Economic Power Index. The Los Angeles metropolitan area also has a gross metropolitan product of $1.0 trillion , making it the third-largest city by GDP in the world, after the Tokyo and New York City metropolitan areas. Los Angeles hosted the 1932 and 1984 Summer Olympics and will host the 2028 Summer Olympics.

Ensenada is a coastal city in Mexico, the third-largest in Baja California. Lying south of San Diego on the Baja California Peninsula, it is locally referred to as La Cenicienta del Pacífico, "The Cinderella of the Pacific". One of the first settlements founded in the Californias, Ensenada has emerged as a cruise ship destination, aerospace center, and a jumping-off point for Valle de Guadalupe, a local wine region. It is said that the first Vitis vinifera made it to the region's San Ignacio Mission in 1703, when Jesuit Padre Juan de Ugarte planted the first vineyards there. Situated on the coastline of Bahía de Todos Santos, the Port of Ensenada is an important commercial, fishing, and tourist port. The city is home to a navy base, army base, and Ensenada Airport, a military airfield. Ensenada is the municipal seat and cultural and commercial center of Ensenada Municipality, one of five into which the state is divided. As of 2020, the municipality had an estimated population of 557,430.