The most populous state in the United States is California. With a population exceeding 39 million residents, it significantly outnumbers other states. California's population growth has been fueled by a combination of immigration, diverse job opportunities, and its attractive climate and lifestyle. Major cities like Los Angeles, San Francisco, and San Diego contribute to its large population density. California's demographic diversity is marked by a mix of cultures, languages, and traditions, making it a vibrant and influential state. It is also the hub of the entertainment industry, technology sector, and agriculture, further solidifying its status as the most populous state.