President and first lady arrive in Houston to meet with people affected by the storm, flooding.
Some have been able to return to assess the damage.
Reservoir releases will flood areas for weeks.
Officials are warning that recovery from the catastrophic rains and flooding could take years.
Half a million barrels of crude oil taken from emergency stockpile.
Harvey hits east of city; more bodies recovered as water begins to recede.
Houston mayor establishes curfew; engineers begin to release water to relieve dams.
A look at Hurricane Carla in 1961 and some of the most damaging hurricanes to hit the US since 2000.