Watch: President Obama speaks at Flint, Michigan, about city's lead crisis

President Barack Obama will speak in Flint, Michigan, around 4 pm as part of his first trip to the city since its lead and water crisis broke into national headlines.

Here's a quick rundown of what happened in Flint, explained by my colleague Libby Nelson:

The Flint water crisis started with a bankrupt city trying to save money. It ended with the declaration of a federal state of emergency after as many as 8,000 children were exposed to a poisonous element that will have lifelong effects on their brain and nervous systems.

Even before the lead crisis, Flint was struggling. About 40 percent of its residents live in poverty. Michigan Gov. Rick Snyder had appointed an emergency manager, an unelected official with near-total control over the city's finances, because Flint was near bankruptcy.

One money-saving move was to stop buying drinking water from Detroit, which charged Flint $21 million in 2011. Flint planned to join a new countywide water treatment system that, like Detroit, drew water from Lake Huron, but that system wasn't yet fully built. So in April 2014, the city began using treated water from the Flint River as a stopgap.

The river water was corrosive. Flint failed to properly treat the water, and the state failed to properly test it. Lead from the city's pipes began leaching into drinking water. In parts of Flint, the percentage of children with high levels of lead in their blood doubled after the switch.

For more, read Vox's explainer.

Watch: Flint's water crisis, explained in 3 minutes