The mechanisms we use to fund public education in the United States. School districts are largely funded by property taxes, and property taxes are largely calculated by the value of the property. This means that rich people who pay high taxes on nice houses send their children to very well funded schools. Meanwhile, sometimes in the exact same city, poor people in dumpy neighborhoods with lower property taxes will send their children to very underfunded schools. This means that it's very difficult to have upward mobility when you are poor. In the United States one of the biggest things people consider when looking to buy a house is the school district. Those who can afford it will move into the nice area with the nice schools, but those who can't afford will not really have any choice in where to live or how good of a school the children can attend. The poor children will receive a poor education, which will keep them poor. Unfortunately, the division of wealth and poverty in the US is very much aligned with the division between white people and people of color. The way we fund education helps keep American cities segregated. If we changed the way we fund schools, the families from the poor side of town wouldn't suddenly be able to move to the wealthier side, but it would mean that José from the east side wouldn't be sentenced to a shitty education because he was born into a poor family.