Birth and death rates are important measurements of population changes. They provide a way to compare health trends and other population information from one year to another or from one community to another. The simplest kind of birth or death rate measures the number of births or deaths in a given year for every 1,000 people. For example, the crude birth rate for the United States is about 14 births for every 1,000 people. The crude death rate is about 8 deaths for every 1,000 people. The death rate is also called the mortality rate. A condition in which the birth rate is equal to the death rate is called zero population growth.