diversity between and within cities does not necessarily mean that there are no
common characteristics.
1.2 What is a City?
There are many definitions of cities in each academic field. In remote sensing
science, several definitions with relating methods for delineating boundaries of cities
have been developed. For example, built-up areas are used in remote sensing science
to detect boundaries of cities (Potere et al. 2009; Bagan and Yamagata 2012; Weng
2012; Giri et al. 2013). Night-time lights have been utilized to identify urban areas
(Zhang and Seto 2011; Levin and Duke 2012). Distances between buildings are
sometimes used to identify the boundaries of cities (Ferreira et al. 2010; Tannier
et al. 2011; Tannier and Thomas 2013). Urban ecology research qualitatively
focuses on the areas under human influence as a city (McIntyre et al. 2008;
Marcotullio and Solecki 2013). Studies in this field have paid attention to built-up
or developed areas to analyze the interactions between human activities and the
natural environment. Thus, the spatial boundaries of cities are quite vague in this
field. Social sciences also attempt to define a city qualitatively. For example, the
impacts of urbanity on human activities have been considered (Tittle and Grasmick
2001; D’Alessio and Stolzenberg 2010). In economics, some studies have examined
the effects of population density on human socioeconomic activities (Gibbons and
Silva 2008; Su 2011), as well as changes in population distribution, employment,
and wealth (Ottaviano and Thisse 2004; Redfearn 2009). Politically administrated
areas are often used in statistical and econometric analyses because of data availability (Bosker et al. 2008; Rosenthal and Ross 2010; Sánchez-Vidal et al. 2014).
Among social sciences, sociology is largely concerned with issues regarding
cities (Giddens 2001). However, even urban sociology has many definitions of cities
and diverse descriptions of cities. In Europe, Georg Simmel referred to a city as a
source of innovation and liberty (Simmel 1950), while Max Weber pointed out the
modernity of cities (Weber 1958; Gianola 2020). They focused on the positive sides
of cities. Views on cities are directly connected to their definitions. Definitions
provided by researchers building on Weber’s thought include densely populated
areas, locations of governments, facilities (physical environment in a broad sense),
municipalities, social relationships, and mental conditions, relationships in the
neighborhood, and places where culture is produced (Fujita 2006).
On the other hand, the American sociologists of the so-called Chicago School
focused on the negative sides of cities, which rapidly grew in 1920s. Louis Wirth, a
central academic researcher in the Chicago School, provided the three tractable
conceptual factors of cities that described or defined the characteristics of cities:
the size of the population, density, and heterogeneity (Wirth 1938). He insisted that
theoretical concepts should be crucial for conducting sociological (empirical)
research on urbanism. However, the three notional factors he provided are not
necessarily useful for defining where cities are spatially located. His interest was
4
S. Muramatsu and K. Mori
common characteristics.
1.2 What is a City?
There are many definitions of cities in each academic field. In remote sensing
science, several definitions with relating methods for delineating boundaries of cities
have been developed. For example, built-up areas are used in remote sensing science
to detect boundaries of cities (Potere et al. 2009; Bagan and Yamagata 2012; Weng
2012; Giri et al. 2013). Night-time lights have been utilized to identify urban areas
(Zhang and Seto 2011; Levin and Duke 2012). Distances between buildings are
sometimes used to identify the boundaries of cities (Ferreira et al. 2010; Tannier
et al. 2011; Tannier and Thomas 2013). Urban ecology research qualitatively
focuses on the areas under human influence as a city (McIntyre et al. 2008;
Marcotullio and Solecki 2013). Studies in this field have paid attention to built-up
or developed areas to analyze the interactions between human activities and the
natural environment. Thus, the spatial boundaries of cities are quite vague in this
field. Social sciences also attempt to define a city qualitatively. For example, the
impacts of urbanity on human activities have been considered (Tittle and Grasmick
2001; D’Alessio and Stolzenberg 2010). In economics, some studies have examined
the effects of population density on human socioeconomic activities (Gibbons and
Silva 2008; Su 2011), as well as changes in population distribution, employment,
and wealth (Ottaviano and Thisse 2004; Redfearn 2009). Politically administrated
areas are often used in statistical and econometric analyses because of data availability (Bosker et al. 2008; Rosenthal and Ross 2010; Sánchez-Vidal et al. 2014).
Among social sciences, sociology is largely concerned with issues regarding
cities (Giddens 2001). However, even urban sociology has many definitions of cities
and diverse descriptions of cities. In Europe, Georg Simmel referred to a city as a
source of innovation and liberty (Simmel 1950), while Max Weber pointed out the
modernity of cities (Weber 1958; Gianola 2020). They focused on the positive sides
of cities. Views on cities are directly connected to their definitions. Definitions
provided by researchers building on Weber’s thought include densely populated
areas, locations of governments, facilities (physical environment in a broad sense),
municipalities, social relationships, and mental conditions, relationships in the
neighborhood, and places where culture is produced (Fujita 2006).
On the other hand, the American sociologists of the so-called Chicago School
focused on the negative sides of cities, which rapidly grew in 1920s. Louis Wirth, a
central academic researcher in the Chicago School, provided the three tractable
conceptual factors of cities that described or defined the characteristics of cities:
the size of the population, density, and heterogeneity (Wirth 1938). He insisted that
theoretical concepts should be crucial for conducting sociological (empirical)
research on urbanism. However, the three notional factors he provided are not
necessarily useful for defining where cities are spatially located. His interest was
4
S. Muramatsu and K. Mori