Riordan Frost
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riordanfrost.bsky.social
Riordan Frost
@riordanfrost.bsky.social
250 followers 110 following 32 posts
Researcher at @harvard-jchs.bsky.social focused on housing, demographics, migration, inequality, and climate change.
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riordanfrost.bsky.social
In just five years, the income needed to afford the median-priced home nearly doubled—from $68k to $131k. Getting payments back to 2020 levels would require interest rates to be nearly zero, per @harvard-jchs.bsky.social
www.jchs.harvard.edu/blog/lower-i...
#FigureFriday #housing #affordability
November 7, 2025 at 3:09 PM
riordanfrost.bsky.social
Happy #MapMonday! How much did each metro area depend on immigration for growth last year, and which ones will therefore feel the effects of the recent slowdown most acutely? Find out in the interactive map in my new @harvard-jchs.bsky.social blog post: www.jchs.harvard.edu/blog/metro-a....
September 8, 2025 at 2:15 PM
riordanfrost.bsky.social
Happy #MapMonday! How much did counties gain/lose from domestic migration in 2024? In my new @harvard-jchs.bsky.social paper, I show that inflows to lower-density places were elevated through 2024. Explore the map: www.datawrapper.de/_/cGxny and the paper: www.jchs.harvard.edu/blog/five-wa...
April 7, 2025 at 6:43 PM
riordanfrost.bsky.social
Happy #MapMonday! Here's a map from my new @harvard-jchs.bsky.social paper on pandemic-era changes in residential mobility! Shifts are emerging in Midwest and Northeast states, while much (but not all) of the Sunbelt keeps drawing more inflows. Explore the map: www.jchs.harvard.edu/blog/five-wa...
This state map shows how annual average net domestic migration changed from the pre-pandemic period (defined as 2010–2011 to 2019–2020) to the post-pandemic period (defined as 2022–2023 to 2023–2024). It shows that in many states in the southeast, inflows accelerated, which was also true for a few states in the Mountain West and New England. Many states in the Northeast and Midwest, on the other hand, had lower outflows after the pandemic than they did before, and several states in these regions also had net outflows before the pandemic but net inflows afterwards. Only a few states, namely California, Hawaii, Massachusetts, Maryland, and Louisiana, had higher outflows than before the pandemic. Most states in the southwest had lower inflows than before the pandemic, and in the Pacific Northwest, Washington and Oregon both had net outflows after the pandemic, a change from having net inflows beforehand.
March 31, 2025 at 1:33 PM
riordanfrost.bsky.social
Happy #MapMonday! What was the largest source of population growth by county in 2024? Immigration played a *big* role, esp. in higher-density areas. Domestic migration remained elevated in lower-density areas. Natural change played a smaller role. Explore the map: www.datawrapper.de/_/U6L0i/
March 24, 2025 at 2:48 PM
riordanfrost.bsky.social
Happy #MapMonday! What was the largest source of population growth in each county in 2023? Many urban counties relied most on natural change, many Sunbelt counties relied on domestic migration, and immigration played a role throughout the country. Explore the map: datawrapper.dwcdn.net/QrDYw/4/.
This county map of the United States shows the largest source of population growth for each county in 2023, between three components: domestic migration, immigration, and natural change. For very few counties, there was net zero or loss in every component. For many urban counties, natural change is the largest component, while for much of the Sunbelt, domestic migration is the largest component. For much of the Midwest and Northeast, immigration was the largest component.
March 10, 2025 at 3:00 PM
riordanfrost.bsky.social
Happy #MapMonday! I’ve been thinking about baby boomers aging into older adulthood (61-79 this year), and it is apparent from this median age by county map that the effects of an aging population will be felt unevenly. Explore the map here: datawrapper.dwcdn.net/xFm4W/2/
March 3, 2025 at 7:04 PM
riordanfrost.bsky.social

Happy #MapMonday! Is the draw of the Pacific Northwest over? There was a notable downturn during the pandemic in net inflows in Washington and Oregon, which were previously migration magnets, especially for young adults. These two maps show the slowdown in 26-34yo net inflows b/t 2019 and 2021.
This is a state map of the United States showing net domestic migration for those aged 26-34 in 2019. It shows that many southern and western states had high net inflows of young adults, while many Midwestern and Northeastern states had outflows. This is a state map of the United States showing net domestic migration for those aged 26-34 in 2021. It shows that many southern states had high net inflows of young adults, while many Midwestern states had outflows. Many western and Northeastern states had lower net inflows.
February 24, 2025 at 2:09 PM
riordanfrost.bsky.social
Happy #MapMonday! Building on recent analysis by @yfreemark.bsky.social & Lindiwe Rennert at @urbaninstitute.bsky.social of the US DOT's plan to prioritize funding to places with high birth and marriage rates, here is a state map showing which states had above-national rates in 2023.
This state map shows which states have birth rates and marriage rates above the national rates in 2023. It shows that states with high birth and marriage rates are concentrated in the Midwest, Southeast, and Mountain West. States with neither are concentrated in the Northeast. A handful of western states have only high marriage rates, and a handful of mostly Midwestern states have only high birth rates.
February 10, 2025 at 7:15 PM
riordanfrost.bsky.social
For #MapMonday, I wanted to add a different angle to the discussion of HUD's 2024 #homelessness point-in-time count by showing changes by state since the onset of the pandemic (i.e. Jan 2020–Jan 2024). Only 4 states had any decline, while 9 states saw increases of 50% or more. [Corrected legend]
February 4, 2025 at 12:53 PM
riordanfrost.bsky.social
Happy #MapMonday! This map of natural population change in 2024 shows that most states had more births than deaths, which is true even for states with net migrant outflows (e.g. CA). Migration or immigration drive population change in most states, though, due to steadily declining natural change.
January 27, 2025 at 8:19 PM
riordanfrost.bsky.social
Happy #MapMonday! Further insight into the surge in immigration in the past few years is now available from the revised 2023 and 2024 estimates from Census Vintage 2024 PEP data. The maps below show that many states have had relatively high immigration rates, even some you might not expect.
A map of immigration rates by state for 2023. It shows that most states gained more than 4 immigrants per 1,000 people in 2023, with the exception of states in New England, the Mountain West, and Appalachia. States with the highest rates including populous states like California, Texas, Illinois, New York, Massachusetts, and Florida, but also less populous states like Rhode Island, Utah, and Nevada. A map of immigration rates by state for 2024. It shows that most states gained more than 4 immigrants per 1,000 people in 2023, with the exception of states in New England, the Mountain West, and Appalachia. States with the highest rates including populous states like California, Texas, Illinois, New York, Massachusetts, and Florida, but also less populous states like Rhode Island, Utah, Kentucky, Iowa, Nebraska, and North Dakota.
January 13, 2025 at 5:27 PM
riordanfrost.bsky.social
Happy #MapMonday! Census 2024 state population estimates came out last month, and the domestic migration patterns are fascinating. Sunbelt is still gaining the most migrants but the flows have slowed, most notably for Texas and Florida. Bonus map to show change from 2023.
This state map shows rates of domestic migration by state in 2023. It shows that the states with the highest rates of inflows are in the Sunbelt and Mountain West, plus Delaware and Maine. States with the highest outflow rates are primarily high-cost states like California, New York, Hawaii, and Massachusetts. This is a map showing net domestic migration rates in 2024. It shows that the states with the highest rates of inflow are in the Sunbelt and Mountain West, though notably this does not include Texas and Florida (which have inflows but not as high). States with high rates of outflows include high-cost states like New York, Hawaii, and California.
January 6, 2025 at 3:22 PM
riordanfrost.bsky.social
One immigration data issue recently has been the discrepancy b/t Census data and CBO estimates on levels of immigration, with CBO estimates being *much* higher. Well, Census retroactively updates its estimates with each new vintage of PEP data, and wow v2024 had a BIG change on immigration numbers:
This chart shows immigration estimates from 2021-2024 according to Census PEP Vintage 2023 estimates versus Vintage 2024 estimates. It shows upward revision in 2022 and 2023, with Vintage 2024 estimates 0.5 million and 1+ million more than Vintage 2023 estimates.
January 3, 2025 at 4:38 PM
riordanfrost.bsky.social
Happy #MapMonday! At this time of year I think much more about how we stay warm, which relates to my state of electrification work from earlier this year. That included an interactive map showing share of HHs using only electricity for various uses (2020 RECS): www.jchs.harvard.edu/blog/decarbo...
These are four state maps showing the share of households using only electricity for space heating, water heating, cooking, and all three. It shows that the highest shares of households using only electricity are in the southeast and Pacific Northwest. It also shows much higher shares using only electricity for cooking, followed by water heating, followed by space heating.
December 16, 2024 at 5:05 PM
riordanfrost.bsky.social
Happy #MapMonday! I've been researching domestic migration in the pandemic years, and one notable finding has been the uptick in rural migration. This county map shows net domestic migration in 2021, when there was a sudden shift in inflows to rural areas (and suburbs and smaller metros).
This is a county map of the United States that shows net domestic migration rates (per 1,000 people) in 2021, showing that rural areas across the country had net inflows that year. It also shows net inflows in the suburban counties of major metropolitan areas.
December 9, 2024 at 3:17 PM
riordanfrost.bsky.social
Happy #MapMonday! This week, a map I made for a @harvard-jchs.bsky.social paper on the history of public housing, which notes that PHA residents are concentrated in the eastern US. Big bonus that the data allowed me to include Puerto Rico! Alex's paper summary: www.jchs.harvard.edu/blog/can-pub...
This map of the United States shows the number of public housing residents by state in 2023. It shows that the states with the highest concentrations of public housing residents are in the eastern half of the country (both north and south), plus Texas and California. Puerto Rico also has a high number of public housing residents.
December 2, 2024 at 3:05 PM
riordanfrost.bsky.social
Happy #MapMonday! (A former Twitter tradition that I'm happy to revive in this cheerier place). Here's a state map showing how much immigrants make up the construction trades workforce around the US, which is substantial in many high-demand states. Source: ACS 2023.
US map showing the immigrant share of the construction trades workforce by state. Shows lower shares in much of the northern part of the country and higher shares in the Sunbelt and high-demand states like New York, California, Texas, and Florida.
November 25, 2024 at 3:04 PM