and necessitate the formation of multiple sub‐centers of employment. Sub‐center formation, however, may not be automatic. At a low population level, equilibrium and optimum coincide, however, as the population expands, the ‘excessive’ population must move away to form a new sub‐center. Given that the social gains from relocation exceed the private gains, the second center is not formed until later. Thus, there may be a role for government in assisting sub‐center formation, through the provision of infrastructure, the regulation of developers, or subsidization of developer activity or firm location.<sup>94,95</sup> At the other extreme to concentrated employment sub‐centers is the case of edgeless cities documented by Robert Lang.<sup>96</sup> An edgeless city is characterized by the development of isolated office and business space separated by large distances between each other. Such business areas are neither pedestrian friendly, nor easily accessible by public transit, and do not lend themselves to mixed use. Policies for curbing sprawl is motivated by the desire to foster agglomeration economies, reduce the cost of providing public services and infrastructure, and reduce the dependence on the automobile and the externalities associated with its use (e.g. air pollution and congestion). Development taxes and congestion tolls seem to be effective in reducing the spatial size of the city. Several anti‐sprawl policies such as UGB, taxes on residential development, property taxes and fuel taxes have been proposed in the literature.<sup>97</sup> Once the urban land use pattern comprises of multiple centers of economic activity and begins to look similar to the congested cities of developed countries, there is a separate set of policy instruments for dealing with congestion externalities. These include ‐ tax on urban auto travel,<sup>98</sup> congestion pricing in the form of cordon charges, area‐wide pricing, and variable‐rate highway tolling (such as that in Singapore, London and in several of U.S. metropolitan areas).<sup>99</sup> Congestion pricing is expected to reduce congestion, thus lessen the associated negative externalities such as like traffic delays, air pollution, and greenhouse gas emissions etc. and also offer revenue to help fund transport system improvements, including public 94 The same issues have been raised on a larger scale in the debates on France’s poles de croissance, Britain’s New Towns Policy, and LDC policies to control growth of primate cities.

95 Developers and large firms (non‐competitive) are sometimes critical in promoting subcenter formation. Edge cities”, as they are popularly known, are subcenters created by large‐scale land developers. See for instance, Henderson and Slade (1993), Henderson and Mitra (1996) and Fujita et al. (1997). Also see Anas et al. (1998) for a survey on subcenters from both the theoretical and empirical points of view. Takashaki (2014) finds that strategic interactions among firms could result in equilibrium with either agglomeration in the city center or decentralization where firms locate at either ends of the city. Higher commuting cost vis‐à‐vis shopping travel costs results in agglomeration, otherwise there is maximum dispersion in firm location decision. Another view is that employment centers emerge as a result of the decision making of local governments, including tax policy and land‐use policy (Fujita, 1989; Sullivan, 1986; Zhang and Sasaki, 1997, 2000) 96 Lang (2003) 97 See for instance, Brueckner (2000b, 2001) who finds that development taxes and congestion tolls seem to be effective in reducing the spatial size of the city. Bento et al. (2006) find that, from an overall efficiency perspective, development taxes and UGB are equivalent instruments and the most effective anti‐sprawl policies. By contrast, gasoline tax and the property tax are substantially less effective in combating sprawl. In an endogenous land use model, Anas and Rhee (2006) find that congestion tolls eliminate excess travel or excess sprawl by making the job and residence distribution of the city more compact while UGBs result in a substantial efficiency loss. Also see Anas and Rhee (2007) that makes a careful discussion on the reasons why UGB is not always a second‐best policy option relative to congestion tolls.

98 Although this may lead to excessive decentralization and perhaps over‐investment in highways such as that in the US in 1950s, see, Wheaton (1978) 99 Santos (2005); Gao (2012) 21