Question: Which  international border is San Ysidro Port of Entry at  

full_context: Document 1: Tecate Port of Entry: The Tecate Port of Entry is one three ports of entry in the San Diego–Tijuana metropolitan region. The land port is located between Tecate, California in San Diego County's Mountain Empire and Tecate Municipality in Baja California. It connects California State Route 188 with Paseo Lazero Cardenas, a spur of Mexico Federal Highway 2, as well as Federal Highway 3 to the south. It is a minor port in comparison to the larger San Ysidro Port of Entry and Otay Mesa Port of Entry. This is attributed in part to the fact that reaching the crossing on the US side requires driving on narrow, winding mountain roads.
Document 2: El Paso–Juárez: El Paso–Juárez, also known as Juárez–El Paso, the Borderplex or Paso del Norte, is a binational metropolitan area, or conurbation, on the border between Mexico and the United States. The region is centered on two large cities: Ciudad Juárez, Chihuahua, Mexico and El Paso, Texas, U.S. Additionally, nearby Las Cruces, New Mexico, U.S. is sometimes included as part of the region, referred to as El Paso–Juárez–Las Cruces or El Paso–Juárez–Southern New Mexico. With over 2.7 million people, this binational region is the 2nd largest metropolitan area (San Diego- Tijuana being the largest) on the United States–Mexico border. The El Paso–Juárez region is the largest bilingual, binational work force in the Western Hemisphere.
Document 3: San Ysidro, San Diego: San Ysidro (] ) is a district of the City of San Diego, immediately north of the U.S.-Mexico border. It neighbors Otay Mesa West to the north, Otay Mesa to the east, and Nestor and the Tijuana River Valley to the west; together these communities form South San Diego, a pene-exclave of the City of San Diego, thus making it possible to travel (by water) between central San Diego and South San Diego without ever leaving the city limits. Major thoroughfares include Beyer Boulevard and San Ysidro Boulevard.
Document 4: San Ysidro Transit Center: San Ysidro Transit Center is a San Diego Trolley station on the Blue Line and the southern terminus for this line. The previous station northwest is Beyer Boulevard. South of this station is the San Ysidro Port of Entry at the Mexico–United States border. The station serves primarily as a way to provide access to downtown for the thousands of international commuters and tourists who travel between San Diego County and Tijuana, Mexico. Its secondary purpose is to provide access to the large shopping areas, including the Las Americas Premium Outlets which are connected to the stop via a pedestrian walkway. An intercity bus station is located adjacent to the station.
Document 5: Paso del Norte International Bridge: The Paso del Norte International Bridge is an international bridge which crosses the Rio Grande (Río Bravo) connecting the United States-Mexico border cities of El Paso, Texas, and Ciudad Juárez, Chihuahua. The bridge is also known as "Paso del Norte Bridge", "Santa Fe Street Bridge", "Puente Benito Juárez", "Puente Paso del Norte" and "Puente Juárez-Santa Fe". The Paso del Norte International Bridge is a four-lane bridge for northbound non-commercial traffic only. The bridge was constructed in 1967. The American side of the bridge is owned and operated by the City of El Paso.
Document 6: San Ysidro Port of Entry: The San Ysidro Port of Entry is the largest land border crossing between San Diego and Tijuana, and the busiest land border crossing in the world. It connects Mexican Federal Highway 1 with Interstate 5 on the U.S. side. The San Ysidro Port of Entry is one of three ports of entry in the San Diego–Tijuana metropolitan region.
Document 7: Mexico–United States border: The Mexico–United States border is an international border separating Mexico and the United States, extending from the Pacific Ocean to the west and Gulf of Mexico to the east. The border traverses a variety of terrains, ranging from major urban areas to uninhabitable deserts. s of 2010 , approximately 350 million legal crossings occur annually, and is the most frequently crossed border in the world.
Document 8: Grossmont Transit Center: Grossmont Transit Center is a San Diego Trolley station located next to Grossmont Center in La Mesa, California. It is located just east of the junction between the Green Line and the Orange Line. It serves a variety of residences, a dense commercial area (including the Grossmont Center Mall), and as a commuter lot. The next station north for both lines is Amaya Drive, the next station west on the Orange Line is La Mesa Boulevard, and the next station west on the Green Line is 70th Street.
Document 9: Las Americas Premium Outlets: Las Americas Premium Outlets is a 560000 sqft outlet mall in San Ysidro, San Diego, California located directly on the Mexico-United States border just west of the San Ysidro Port of Entry at the new PedWest crossing from Tijuana to Virginia Avenue on the U.S. side.
Document 10: Canada–United States border: The Canada–United States border (French: "Frontière entre le Canada et les États-Unis"), officially known as the International Boundary, is the longest international border in the world between two countries. It is shared between Canada and the United States, the second- and fourth-largest countries by area, respectively. The terrestrial boundary (including portions of maritime boundaries in the Great Lakes, and on the Atlantic, Pacific, and Arctic coasts) is 8,891 km long, of which 2,475 km is Canada's border with Alaska. Eight Canadian provinces and territories (Yukon, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, and New Brunswick), and thirteen U.S. states (Alaska, Washington, Idaho, Montana, North Dakota, Minnesota, Michigan, Ohio, Pennsylvania, New York, Vermont, New Hampshire, and Maine) are located along the border.
Document 11: Geography of Mexico: The geography of Mexico describes the geographic features of Mexico, a country in the Americas. Mexico is located at about 23° N and 102° W in the southern portion of North America. From its farthest land points, Mexico is a little over 3,200 km in length. Mexico is bounded to the north by the United States (specifically, from west to east, by California, Arizona, New Mexico, and Texas), to the west and south by the Pacific Ocean, to the east by the Gulf of Mexico, and to the southeast by Belize, Guatemala, and the Caribbean Sea. The northernmost constituent of Latin America, it is the most populous Spanish-speaking country in the world. Mexico is the world's 13th largest country, three times the size of Texas.
Document 12: Otay Mesa Port of Entry: The Otay Mesa Port of Entry is one of three ports of entry (POE) in the San Diego–Tijuana metropolitan region, connecting Otay Mesa in the City of San Diego with the Otay Centenario borough of Tijuana. The facility was opened in 1983, and was constructed primarily to divert growing commercial truck traffic from the busy San Ysidro Port of Entry. Since then, significant passenger vehicle and pedestrian traffic has grown as development in the area around the crossing has grown. Commercial importations through Otay Mesa accounts for billions of dollars worth of freight.
Document 13: Interstate 805: Interstate 805 (I-805) is a major north–south Interstate Highway in Southern California. It is a bypass of I-5, running roughly through the center of the Greater San Diego region from San Ysidro (part of the city of San Diego) near the Mexico–U.S. border to near Del Mar. The southern terminus of I-805 at I-5 in San Ysidro is less than a mile north of the Mexican border. I-805 then traverses the cities of Chula Vista and National City before reentering San Diego. The freeway passes though the San Diego neighborhoods of North Park, Mission Valley, Clairemont, and University City before terminating at I-5 in the Sorrento Valley neighborhood near the Del Mar city limit.
Document 14: United States Boundary Commissioner: Article V of the TREATY OF PEACE, FRIENDSHIP, LIMITS, AND SETTLEMENT BETWEEN THE UNITED STATES OF AMERICA AND THE UNITED MEXICAN STATES CONCLUDED AT GUADALUPE HIDALGO (known commonly as the Treaty of Guadalupe Hidalgo ) declared that the new boundary between the two republics of the United States and Mexico would lay "three leagues from land, opposite the mouth of the Rio Grande, otherwise called Rio Bravo del Norte, or Opposite the mouth of its deepest branch, if it should have more than one branch emptying directly into the sea; from thence up the middle of that river, following the deepest channel, where it has more than one, to the point where it strikes the southern boundary of New Mexico; thence, westwardly, along the whole southern boundary of New Mexico (which runs north of the town called Paso) to its western termination; thence, northward, along the western line of New Mexico, until it intersects the first branch of the river Gila; (or if it should not intersect any branch of that river, then to the point on the said line nearest to such branch, and thence in a direct line to the same); thence down the middle of the said branch and of the said river, until it empties into the Rio Colorado; thence across the Rio Colorado, following the division line between Upper and Lower California, to the Pacific Ocean. " It delineated the boundary through its text but wasn't written with much knowledge of the area's actually geography; A commissioner and surveyor from each country were appointed to precisely locate landmarks and accurately map the new border, relying on the treaty as their guide.
Document 15: List of companies of Mexico: Mexico is a federal republic in the southern half of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Covering almost two million square kilometers (over 760,000 sq mi), Mexico is the sixth largest country in the Americas by total area and the 13th largest independent nation in the world. With an estimated population of over 127 million, it is the eleventh most populous country and the most populous Spanish-speaking country in the world while being the second most populous country in Latin America. Mexico is a federation comprising 31 states and a federal district that is also its capital and most populous city. Other metropolises include Guadalajara, Monterrey, Puebla, Toluca, Tijuana and León.
ground_truth: The Mexico–United States border