After adding over 934,000 new cases throughout the last week, the U.S. now has more than 42.1 million confirmed cases of COVID-19. There have been more than 670,000 COVID-19-related deaths — the highest death toll of any country.

New cases continue to rise at a steady rate. In the past week, there were an average of 45.1 daily new coronavirus cases per 100,000 Americans — essentially unchanged from the week prior, when there were an average of 49.5 daily new coronavirus cases per 100,000 people.

While COVID-19 has spread to nearly every part of the country, cities continue to be the sites of major outbreaks. Experts agree that the virus is more likely to spread in group settings where large numbers of people routinely have close contact with one another, such as colleges, nursing homes, bars, and restaurants. Metropolitan areas with a high degree of connectivity between neighborhoods and a large population may be particularly at-risk.

The Denver-Aurora-Lakewood, CO, metro area consists of Denver County, Arapahoe County, Jefferson County, and seven other counties. In the past week, there were an average of 28.5 new coronavirus cases every day per 100,000 Denver residents, less than the national figure. The metro area’s average daily case growth in the most recent week is essentially unchanged from the week prior, when there was an average of 29.1 daily new cases per 100,000 Denver residents.

The spread of coronavirus depends on a variety of factors and can vary even between neighboring counties. Within the Denver-Aurora-Lakewood metro area, COVID-19 is growing the fastest in Gilpin County. There were an average of 58.3 new cases per day per 100,000 residents in Gilpin County during the past week, the most of the 10 counties in Denver with available data.

Case growth in the Denver metro area varies at the county level. In Denver County, for example, there were an average of 25.1 new cases per day per 100,000 residents in the past week — the least of any county in Denver and more than the case growth rate in Gilpin County.

While Gilpin County is driving the growth of COVID-19 in the Denver area, it does not have the highest incidence of cases overall. As of September 23, there were a total of 6,347.6 confirmed cases per 100,000 residents in Gilpin County, the ninth most of the 10 counties in the metro area. For comparison, the U.S. has so far reported 12,985.5 cases per 100,000 Americans nationwide.

In order to slow the spread of COVID-19, city and county governments have ordered the closure of thousands of consumer-facing businesses. These measures have led to widespread job loss and record unemployment. In Gilpin County, unemployment peaked at 23.3% in April 2020. As of June 2021, the county’s unemployment rate was 7.2%.

To determine the county in every metropolitan area where COVID-19 is growing the fastest, 24/7 Wall St. compiled and reviewed data from state and local health departments. We ranked counties according to the average number of new daily COVID-19 cases per 100,000 residents in the seven days ending September 23. To estimate the incidence of COVID-19 at the metropolitan level, we aggregated data up from the county level using boundary definitions from the U.S. Census Bureau. Population data used to adjust case and death totals came from the U.S. Census Bureau’s 2019 American Community Survey and are five-year estimates. Unemployment data is from the Bureau of Labor Statistics and is not seasonally adjusted.

These are all the counties in Colorado where COVID-19 is slowing (and where it’s still getting worse).

Rank in MSA	County	Population	New daily cases per 100,000, week ending September. 23	New daily cases per 100,000, week ending September. 16	Cumulative cases per 100,000	Cumulative deaths per 100,000
1	Gilpin County	6,018	58.3	32.6	6,347.6	49.9
2	Clear Creek County	9,495	44.7	51.4	7,119.5	42.1
3	Elbert County	25,717	44.6	42.0	9,048.5	70.0
4	Douglas County	336,041	33.3	35.8	10,843.3	78.0
5	Broomfield County	67,886	30.8	26.6	8,885.5	114.9
6	Adams County	504,108	30.1	32.4	13,813.3	155.5
7	Jefferson County	574,798	28.3	26.2	9,905.6	149.6
8	Park County	17,867	27.6	34.6	6,324.5	39.2
9	Arapahoe County	644,560	27.3	30.9	11,266.4	123.2
10	Denver County	705,576	25.1	23.4	11,953.4	126.8

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