How do gerrymandering relate to the idea of one person-one vote

In ideal conditions, the one person one vote idea would make an ideal way for democracy. Each person votes and the votes are treated equally and we get a good democratic process. However, gerrymandering influences this because you organize the districts in such a way that unwanted votes are outnumbered by wanted votes. For example, there is a huge African-American community that could affect the statewide electoral voting. Since racist people would like to disenfranchise the voters, they would draw the districts in such a way that the huge African-American community loses its power through being separated into various smaller groups where other votes outnumber them.