Do big city marathons (e.g. Boston, New York City, Chicago) have more runners from the home state of the race? Does a a home state advantage exist in terms of participation for these races?
Although I have not examined the data, I would think that local races primarily have participants that reside in geographic areas surrounding the race. Makes sense to me. But are big city marathons different? Is the runner distribution by state of residence more diverse? Perhaps the distribution resembles the overall population distribution by state (i.e. California is the most populous state and, consequently, the most runner participants).
Below is the data. I compiled the number of finishes by U.S. states for the 2017 Boston Marathon, 2016 New York City Marathon, and 2016 Chicago Marathon. (Source: Marathon website results page).
It seems the home state advantage exists with approximately 50% of Chicago and New York City Marathon finishers from the home state. Although not 100% (like you might expect in a local race), 50% is sizeable large given a +20,000 participant field. Interestingly, although the effect exists, it is less apparent at the Boston Marathon (30% home state), perhaps due to the unique qualifying standards for the race.