Los Angeles County, California is 275 times larger than Jersey City, New Jersey.
Area: 38 km2 calculated
Jersey City is the seat of Hudson County, New Jersey. As of the 2010 United States Census, the population of Jersey City was 247,597, making it the second-most populous city in New Jersey, after Newark. Wikipedia
Area: 10,580 km2 calculated
Los Angeles County, also known as L.A. County, officially the County of Los Angeles, is a county in the U.S. state of California. As of the 2010 U.S. Census, the county has a population of 9,818,605, making it the most populous county in the United States. Wikipedia