This thesis consists of five individual essays, and a common introduction, sharing the general idea that the location of economic activities matters. Four of the essays explicitly introduce a transport sector that has impacts on the location and economic efficiency of other activities. The two first essays are of an empirical nature and the three last are purely theoretical. The empirical essays are based on data related to the county of Jönköping. However, the data originate from two different sources. The first essay builds on data collected through a survey, and the second essay builds on official statistics collected by Statistics Sweden. The first essay deals with the concept of transport quality and the variation of transport quality over different firm-specific characteristics. The second essay brings forward the economic sources of the relative growth of a leading manufacturing region in Sweden, the Gnosjö region. The third essay demonstrates how spatial concentration is influenced and constrained by the cost of transportation. The fourth essay applies standard club theory to show that there are efficiency gains to be made in co-ordinating the use of transportation. The fifth paper shows how two different policies influence economic growth and the concentration of economic activity. The two policies investigated are targeted at transport costs and spillovers of knowledge between regions.