How and why have the political ward boundaries changed?
Wards are just like any other political division, though they are perhaps the smallest politically-relevant one possible.
As with other political boundaries, they are subject to be being redrawn by the political entity responsible for them. In this case, wards are almost always a function of city government, though in rural areas, they can often fall to county government.
What triggers a ward redrawing can be myriad: requirements from the city/county charter, state-level requirements, or even merely desire by the responsible government entity. Typically, changes in resident population are the most common, though they can often also be a result of zoning and redistricting changes. Wards may also need to be redone when the "owning" government entity changes, so (for example) if a formerly unincorporated area is brought under control of a city government, new ward boundaries are likely to be created.
Note that wards are mostly irrelevant today - they almost always serve merely as a convenient way to determine where voting is done for local residents of the ward, and little else. Consequently, there is generally very little incentive or desire to redraw existing ones.
Natural boundaries are coastlines, mountain ranges, lakes, rivers, gulfs, canyons, desert wastelands... basically, a part of the earth that is considered by most to be uninhabitable. Political boundaries are the borders that are represented on maps by all the other lines besides natural boundaries and latitude/longitude indicators (although many political boundaries are natural boundaries and parts of lines of latitude and longitude). They are the boundaries between nations and between national subdivisions.
A political unit such as a state is divided into districts for the purpose of electing representatives to a legislative body. If the basis of election is population, with equal number of people represented by each elected member, the boundaries of the district must be changed after each census if the population changes. This is called redistricting (drawing new district boundaries).
The two opposing ideologies that waged the Cold War and created two major political boundaries were?
Cartography is the art and science of map making. Physical map shows or describes the physical features on the surface of the earth(or mapping surface) like the water bodies, forests, mountains etc,. in a cartographic representation(like points, polygons,or lines). A political map only shows the political boundaries of the country( or the selected entity) like the International boundaries, state boundaries, district boundaries and the capital cities of the states etc,.
There are three types: International political boundaries, between Mexico and other three countries: the United States, Guatemala and Belize. The federal boundaries, which define each one of Mexico's 31 states and Federal District. The municipal boundaries, akin to US counties, which subdivide each of Mexico's states. In the case of the Federal District, it is subdivided into "delegaciones" or boroughs.