Hi Reddit,

My name is Alasdair Rae and I am Senior Lectuer in Urban Studies and Planning at the University of Sheffield, in England. My research focuses on geographic analysis, and particularly on how places connect, or not. One of the main things I'm interested in is the difference between political boundaries, such as counties and states, and how this compares with patterns of human connection on the ground, such as commuting and migration.

And I'm Garrett Dash Nelson; I'm a postdoctoral fellow in the Society of Fellows and the Department of Geography at Dartmouth College in New Hampshire. I work on the history of geographic problems in planning, and I'm interested in how the human landscape and social action structure one another.

Last month, we published a paper titled "An Economic Geography of the United States: From Commutes to Megaregions" in the journal PLOS ONE . We were curious what would happen if we tried to divide the geography of the United States up by using data about millions of Americans' commuting habits, instead of relying on old borders like state and city lines. We tried two ways of interpreting the data. First, we made "flow maps," which allowed us to visually interpret where clusters of commuters are congregating. Second, we used an algorithm to do what's called "community detection"—finding groups of closely related points within a network of complex interrelations. We ended up with a new map of the United States that offers a new way of thinking about what kind of areas match the geographic patterns of our real lives.

We'll be answering your questions at 1pm ET -- Ask Us Anything!

Follow Alasdair on Twitter @undertheraedar and Garrett on Twitter at @en_dash