Background: Colorectal cancer (CRC) is typically considered a disease that affects older adults. However, recently a concerning increase in the incidence rates of CRC among young adults (age < 50) has been noted. Given the limited analysis of colorectal cancer mortality assessing for age-based differences, we aimed to characterize trends in mortality rates of CRC between 1999 and 2020 in the United States, with the hypothesis that younger patients would also experience an increasing morality rate from CRC in concert with the increasing incidence. Methods: We queried the Centers for Disease Control database for mortality statistics with an underlying cause of death of colon and rectal cancer between the years 1999 - 2020. Crude mortality rates (CMR) were calculated per 100,000 deaths. Patients were stratified based on early-onset (30-49 years), average-onset (50-69 years), and late-onset (70+ years) CRC. For each cohort, we examined race and U.S. Census Region variables to assess drivers in mortality. Temporal trends were assessed using Joinpoint regression software. Average annual percent change (AAPC) were considered statistically significant if p < 0.05. Results: Between 1999 and 2020, 1,166,158 deaths due to CRC occurred and the CMR decreased from 20.3 to 15.7. For patients aged > 70, colorectal cancer mortality rate decreased from 148.6 to 75.9 at an average of 3.2% annually during this time frame. For the group aged 50-69, there was a decrease in CMR from 32.7 to 24.2, reflecting an average annual decrease of1.4%. In patients aged 30-49, CMR increased from 3.6 to 4.2, reflecting an average annual percent increase in mortality of 0.7%. This increase in CRC mortality in the youngest cohort occurred independent of geographical location. Mortality in young adults increased the fastest in the West at a rate of 1.1% annually and slowest in the South at 0.4% annually. Similar increases in mortality rates were identified when cohorts were stratified by race, with Non-Hispanic American Indian/Native American populations experiencing the most rapid increases in mortality at 3.4% annually. Conclusions: These results demonstrate age-related disparities in recent CRC mortality trends. While the overall mortality of CRC has decreased over the last two decades, this decrease was largely due to declining mortality in older adults. In contrast, younger adults experienced a sharp rise in CRC mortality rates, increasing at an average annual percentage increase of almost 1% each year independent of racial or geographic factors. These results highlight a concerning emerging trend with significant public health implications and provide rationale for increased surveillance in young adults.