In the United States the average life expectancy hovers around 78 years. This number is on the rise. In 2015, life expectancy reached 79 years. It is due to a number of factors such as improvements in medicine and lifestyle. In the United States, life expectancy averages around 78 years. This number has increased in recent years. In 2015, life expectancy in the United States was 79 years. It is due to a number of factors, including advances in medicine and lifestyle improvements.