Death rates in the 20th century 1 year old. In 1999, at the end of the century, the infant mortality rate in the United States declined more than 90% to 7.2 deaths per 1,000 live births. Similarly, maternal mortality rates declined almost 99% to less than 0.1 reported deaths per 1,000 live births. There are a variety of causes for this steep decline in death rates in the 20th century: Despite these tremendous decreases in infant mortality and maternal mortality, the 20th century experienced significant disparities between minority death rates compared to death rates for white mothers. In the 1900s, black women were twice as likely
20th century in ichnology excavation of fossil footprints in history. In the Lee Stokes reported unusual footprints he interpreted as the first known pterosaur tracks. This attribution would be controversial much of the rest of the century but has since been vindicated. The dinosaur footprints of Dinosaur Ridge in Colorado were also discovered and studied in the 20th century. The advent of the dinosaur renaissance and the publication by R. McNeil Alexander of a formula which could reconstruct their running speed based on data from fossil trackways brought renewed interest and prestige to ichnology during the late 20th century. This led to several symposia