California is projected to lose a congressional seat for the first time next year, while states President Trump won such as Texas and Florida will likely gain seats, according to an analysis of new Census data by the Brookings Institution's William Frey.

Why it matters: It only takes a handful of seats to shift a party's power in Congress for a decade. The new data underscores the need for an accurate 2020 Census count, especially with changing demographics in states with booming populations such as Florida, Texas and Arizona.

By the numbers: If the rate of population change from July 2018 to July 2019 holds into the next year...

Blue states including New York, Illinois, Rhode Island and California are projected to each lose a seat.

including New York, Illinois, Rhode Island and California are projected to each lose a seat. Red states such as Texas, Arizona, Montana, Florida and North Carolina are projected to gain.

What to watch: Demographics are shifting in states like Florida, Texas and Arizona, which have seen an influx of Latinos who tend to skew more Democratic and are more likely to be undercounted by the census, Frey said. Texas has slowly been turning blue, and Florida has been tightly contested for years.

Three key swing states that voted for Trump in 2016 — Michigan, Ohio and Pennsylvania — are each projected to lose a congressional seat.

that voted for Trump in 2016 — Michigan, Ohio and Pennsylvania — are each projected to lose a congressional seat. Redistricting will play a crucial role in determining how much a political party benefits from congressional reapportionment. It will have a significant impact on elections in the next decade.

The big picture: The changes come as total population growth in the U.S. reaches its lowest point since 1918 at just 0.48%.

For the first time in decades, the number of births minus the number of deaths was less than 1 million in the U.S., the AP reports.

the number of births minus the number of deaths was less than 1 million in the U.S., the AP reports. With the aging of the population, as the baby boomers move into their 70s and 80s, there are going to be higher numbers of deaths,” Frey said.

as the baby boomers move into their 70s and 80s, there are going to be higher numbers of deaths,” Frey said. Four states had more deaths than births: West Virginia, Maine, New Hampshire and Vermont.

Go deeper: The U.S. communities in danger of being overlooked in the 2020 census