The U.S. is older, more diverse, more urbanized and growing slower overall than in past decades, according to data from the 2020 Census released on Thursday.

Why it matters: The decennial Census provides a snapshot of the ever-changing demographics of the U.S. — and sets up the partisan fight over how states will redistribute electoral power for the next decade through redistricting.

The big picture: Almost all of the country's population growth occurred in large metro areas over the decade. For the first time, all 10 of the largest U.S. cities have more than 1 million people.

• And rural areas shrunk as cities grew: More than half of U.S. counties saw their overall populations decline compared to 2010, Marc Perry, a senior demographer at the Census Bureau said during the press conference.

Also for the first time ever, there was an overall decline in the non-Hispanic white population.

• The U.S. is more diverse overall than a decade ago. There was a 61.1% chance nationally that two people chosen at random were from different races or ethnicities.

What to watch: Some states have rapidly approaching redistricting deadlines, cut offs for candidate filings and primary dates. The delayed Census results will force expedited map-drawing — and any litigation that ensues.

• Party officials, attorneys and experts will have an eye on states that are gaining or losing Congressional seats— like Texas, Florida, North Carolina, New York and Illinois. The new Census data provides a better sense of where extra seats might go in some states and which areas might lose representation in others.
• The Census released the data in what is called the legacy format, which is a less-easily digestible. It could take days for some state redistricting officials to convert the data into maps. A more user-friendly version of the data will be released at the end of September.