However, a lot of these benefits from ports spill over to other regions. Firms in other regions also benefit from efficient ports when exporting and importing, and links with other sectors mostly take place outside the port region. Less than 5% of the economic linkages with suppliers take place in the port or the port-region, with a larger share in the main economic centre of the country, which could be relatively far away from the port, e.g. Ile-de France for the ports of Le Havre and Marseille; and Bavaria and Baden-Württemberg for the port of Hamburg.Ports also have negative port impacts, mostly related to the environment, land use and traffic congestion. These impacts can be very substantial; e.g. more than half of the SO 2 -emissions in Hong Kong are related to shipping, and a third of the land surface of the city of Antwerp consists of its port. In addition, port truck traffic accounts for more than 85 % of total truck traffic on some sections of the highways in Los Angeles. Most of these negative impacts are localised, taking place close to the port area (in terms of noise and dust) and in the metropolis (for air emissions, water quality, congestion and land use). This represents what can be called the port-city mismatch: the combination of benefits spilling over to other regions and localised negative impacts. How to solve this mismatch?Evidently, the port needs to be competitive if cities want to benefit from it. Port-related value added and employment is strongly related to urban wealth. Ports can be made more competitive by strengthening their maritime links, port operations and hinterland connections. Local goodwill for port functions in cities is essential and can be earned. Environmental policies and incentive schemes have reduced a variety of environmental impacts, transport policies in and around ports have mitigated congestion and port relocations have freed up centrally located urban land for other functions. However, the key issue is how to get more local value for money out of ports.