  Social media content shared today in cities, such as Instagram images, their
tags and descriptions, is the key form of contemporary city life. It tells
people where activities and locations that interest them are and it allows them
to share their urban experiences and self-representations. Therefore, any
analysis of urban structures and cultures needs to consider social media
activity. In our paper, we introduce the novel concept of social media
inequality. This concept allows us to quantitatively compare patterns in social
media activities between parts of a city, a number of cities, or any other
spatial areas. We define this concept using an analogy with the concept of
economic inequality. Economic inequality indicates how some economic
characteristics or material resources, such as income, wealth or consumption
are distributed in a city, country or between countries. Accordingly, we can
define social media inequality as the measure of the distribution of
characteristics from social media content shared in a particular geographic
area or between areas. An example of such characteristics is the number of
photos shared by all users of a social network such as Instagram in a given
city or city area, or the content of these photos. We propose that the standard
inequality measures used in other disciplines, such as the Gini coefficient,
can also be used to characterize social media inequality. To test our ideas, we
use a dataset of 7,442,454 public geo-coded Instagram images shared in
Manhattan during five months (March-July) in 2014, and also selected data for
287 Census tracts in Manhattan. We compare patterns in Instagram sharing for
locals and for visitors for all tracts, and also for hours in a 24-hour cycle.
We also look at relations between social media inequality and socio-economic
inequality using selected indicators for Census tracts.
