The products of architecture and planning are metaphors for human civilization. In them can be seen the hopes, fears and aspirations of each period and each place in human history. They are a physical response to phenomenal change.
During the 19th Century, long distance travel was reduced in time from months and weeks and then to weeks and days. In the 20th Century it was reduced to days and hours. Short distance personal travel was reduced from weeks and days to hours and minutes.
In the 19th Century personal communication (by signs) was reduced from months and weeks to minutes. In the 20th Century voice communication became common.
In the last half of the 20th Century, the ability to deliver nation-destroying crushing military force over great distances was reduced to minutes.
All of these phenomena tended toward centralization. Industrial Age development and design in the 19th and 20th Century sought to create an artificial world, replacing the natural world in the process. It continues to consume large quantities of natural resources without regard to future availability, retaining relatively little and discarding the remainder. Energy is created by burning fossil fuels, powering the industrial enterprise primarily by heat-transfer, an archaic technology, polluting and destabilizing the natural global environment in the process. Its architecture reflects a tendency toward universal uniformity which disregards variations in climate and geography and in unique local conditions.
In the last decade of 20th Century personal communication was reduced to seconds, worldwide. An idea can now be shared almost as soon as its articulated.
In the late 20th Century, the pattern of local ground transportation along spokes radiating from hubs (cities) steadily changed to a lattice pattern of of movement from node to node. Long distance air transportation, despite the creation of airport hubs, has assumed a similar pattern, which can be seen by overlaying airline route maps.