You’ve seen the headlines: Philly is growing. The city’s population has been increasing for the last seven years after decades of decline, with a boom in retirees, millennials and immigrants. The question arises: Where the heck are all these new people coming from?

Thanks to a tool from the good people at the U.S. Census, we can figure that out. The Census Flows Mapper tells us how many people, on average, moved to Philadelphia annually from 2008-2012 from a given location, based on American Community Survey Data. The data only provides domestic movers (FWIW, Philadelphia’s foreign-born population has increased from about 151,000 to 185,000 in that timeframe), so we can’t tell exactly where all the new Philadelphia residents are from, but it’s a start. So Billy Penn analyzed where these new Philadelphians are coming from, whether Philadelphia is taking more people from other big cities than it’s losing, and how many people are headed to the ‘burbs.

The great migration map

In the last few years, around 50,000-60,000 people have been annually moving into Philadelphia County from other domestic locations (and about 10,000-15,000 from abroad). Each colored-in county on this map has sent an annual average of at least one mover to Philadelphia from 2008-12. Most of the people are coming from the East Coast with a decent amount from the West. With all those blanks spaces in the middle, Philadelphia is not exactly enjoying a heavy dose of Midwest flavor.

For more specific numbers, here’s a Google map of the counties (plus Washington D.C. and New York City) from which Philadelphia has received 200 people or more annually from 2008-2012. Zoom in and click on a symbol for the county name and the number of people who have moved annually. Red symbols feature places from which 1,000 or more people have moved, yellow 600 to 1,000, light blue 300 to 600 and purple 200 to 300.

As you’ll notice by the map, most Philly movers are clustered around Philadelphia. The great majority of our new residents are former suburbanites from Montgomery (5,265), Delaware (5,332), Chester (1,496), Bucks (3,749), Camden (1,850) and Burlington Counties (1,148). Not surprisingly, Philadelphia is still comprised largely of Pennsylvanians and people hailing from nearby.

But the city is getting many move-ins from around the country. In 2012, according to Census Data, Philadelphia’s population of people not born in Pennsylvania but born in the United States was about 263,000, compared to about 244,000 in 2000. This mapping tool does not provide for an age function so you can tell the age ranges of people coming from exact locations, but here’s why we can tell most of them are young. According to Census data, the median age of people moving to Philadelphia in 2012 who had lived in a different state the previous year was 24.8 (for people moving to Philadelphia from another county in Pennsylvania, the median age was 24.3). Here are the top 10 “cosmopolitan” places from which Philadelphia is attracting people (places that are not suburbs, not in Pennsylvania and not in New Jersey).

New York City: 3,087 Washington D.C.: 939 Baltimore County/City: 670 Montgomery County, Md. (DC Metro area): 558 Cook County, Ill. (Chicago): 546 Los Angeles County: 482 Orange County, CA: 389 Fairfield County, CT: 352 Suffolk County, Mass. (Boston): 301 Miami-Dade County, Fla.: 298

If people leave Philly, where are they going?

Attracting new people to come to Philadelphia is just one part of turning this city around. The other part is keeping them here; if you know how do that, call the mayor’s office because Michael Nutter would like to know, too.

Schools, jobs and crime are all reasons why Philadelphia leaders are worrying whether the boom will last. And sure enough, more people are still moving from Philadelphia to the suburbs than from the suburbs into Philadelphia, with an annual average net loss of -8,077 from 2008-2012.

Gloucester County: +234

Bucks County: +216

Chester County: -347

Camden County: -649

Delaware County: -940

New Castle County, Del.: -1737

Montgomery County: -4,854

For migration to/from other big East Coast cities, the news is better but still not great. Philly has been gaining more people from D.C., Baltimore and Boston than it has been losing to those cities. That’s also the case with millennial hotbeds like Austin and Nashville — but not with America’s other biggest cities, like Chicago, Houston or Los Angeles. Philadelphia County’s average annual net migration flow from 2008-2012 these places was -146, and it breaks down like this.

Washington D.C.: +433

Davidson County (Nashville): +169

Travis County (Austin): +149

Baltimore: +117

Suffolk County (Boston): +19

Allegheny County, Pa. (Pittsburgh): -48

Denver County, Col.: -78

Cook County, Ill. (Chicago): -120

Harris County, Texas (Houston): -151

San Francisco County, Calif.: -174

Los Angeles County, Calif.: -219

New York City: -243

Another concern for Philadelphia is losing talented people. We can’t exactly tell how “talented” some of these people are, but we can see the net flow of employed individuals to the suburbs or to the other big east coast cities. It doesn’t look great for Philadelphia in this category, either. The suburbs have been getting more employed Philadelphians than Philadelphia has been getting employed suburbanites in many cases, with an annual average net loss of -2,505 from 2008-2012.

Bucks County: +399

Burlington County: +179

Delaware County: +61

Gloucester County: +55

Chester County: -296

Camden County: -477

New Castle County: -694

Montgomery County: -1,732

Washington D.C. was the only East Coast big city from which more employed people were leaving to go to Philadelphia than vice versa from 2008 to 2012, but the average annual net loss of -469 was not major. Here’s how it breaks down:

Washington D.C.: +46

Baltimore: -55

Suffolk County (Boston): -99

New York City: -361

You might be wondering how Philadelphia’s population has been increasing the last several years if it still has a major net loss to the suburbs and a slight net loss to those major cities. Remember: immigrants and newborns are also driving some of the growth and, despite the net loss when taking into account those big cities the last few years, the number of out-of-staters living in Philadelphia is still almost 20,000 greater than it was in 2000.

The Washington D.C. comparison

What’s the best way to compare all this data? The Census Flows Mapper only has datasets from 2008-12, 2007-11 and 2006-10 so there’s a little too much overlap to compare the most recent Philadelphia movers to an earlier timeframe. So let’s compare it to our southern neighbor, Washington D.C., long a hub for governmental jobs and another booming city for millennials.

Despite D.C. being a renowned city for transplants, Philly grades out pretty similar from 2008 to 2012. D.C. featured 32 places not including its suburbs from which it had an average of 200 or more annual movers, and Philadelphia had 34, not including its suburbs. When it came to net flow from other big or trendy areas, however, Washington outdoes Philadelphia. It had a positive net flow for all the places discussed for Philadelphia above except for New York City and Travis County (Austin).

Washington D.C.’s population of 658,000 is also roughly 45 percent the size of Philadelphia. Nevertheless Philadelphia boasts a similar diversity of domestic move-ins as our nation’s capital. Not bad.

Like Philadelphia, Washington D.C. is also experiencing major losses to the suburbs. It has a negative net flow of people to all of its surrounding suburban counties, as you can see by this map.

Plus, as you saw before, Philly is winning the net migration battle with Washington D.C. for the overall population and for employed people. Point, Philadelphia.