How and why have the political ward boundaries changed?

Answer 1

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.

Answer 2

Political ward boundaries can change due to population growth or shifts, community needs, or legal requirements such as equal representation. Redistricting or reapportionment processes are often initiated based on census data to ensure fair and equal representation in political decision-making. Boundaries may be adjusted to reflect demographic changes and maintain the principle of one person, one vote.