last mile
The portion of the infrastructure that carries communication signals from the main system to the end user's business or home, often involving greater expense to install and maintain, and lower transmission speeds.
last mile: the expensive final stretch to your door
The last mile is the physical segment of a telecommunications network that reaches from the service provider's distribution point to the customer's premises. In practice, this means the copper pair, fiber optic strand, coaxial cable, or wireless link that sits between the edge of the operator's network infrastructure and your building's entrance. For a residential customer, it might be a single twisted pair running from the street cabinet to the house jack. For a business, it could be a dedicated fiber connection terminating at the demarcation point in the lobby.
This final segment handles radically different economics than the trunk lines feeding the network. Backbone fiber routes can serve thousands of customers per cable; a last mile circuit serves one. Installation costs per subscriber remain high even in densely developed areas, and maintenance visits are frequent and geographically dispersed. A network operator might spend more on last mile infrastructure and operations than on all the long-haul transmission combined, which is why rural broadband deployment remains unprofitable without subsidy.
Variants and practical reality
The phrase covers several different physical technologies. Copper twisted pair delivers DSL and legacy telephone service; coaxial cable carries cable modem broadband; fiber offers the highest speeds but highest installation cost; fixed wireless and satellite serve areas where wired infrastructure cannot justify the expense. The term also applies to water mains, gas lines, and electricity distribution, where the same economics and engineering challenges appear: the local connections to individual users drive cost per unit far higher than the main transmission plant.
Speed and latency degrade in the last mile because of signal attenuation over longer distances at lower frequencies, and because the infrastructure is older and less standardized than backbone networks. A 100 Mbps fiber connection might deliver exactly that from the street cabinet onward, but copper service running 300 meters from the exchange cabinet to the premises will be limited by line characteristics: typical DSL rates top out around 15 to 25 Mbps depending on distance and line quality. Copper pairs also remain susceptible to interference and moisture ingress, making them the weak point in modern broadband networks.
The term entered common usage in the 1990s as deregulation opened telecommunications to multiple operators, making the cost structure of network segments more visible and discussable. It remains current in broadband policy, infrastructure investment, and network engineering because the economic and technical constraints it names have not fundamentally changed.