A grid system make it easier to find A LOCATION on a map. The grid references define locations on maps by using Cartesian coordinates. The grid lines used on maps define the coordinate system and they are usually numbered to provide unique references to features.
They were all service programs by President Kennedy
Peace Corps were established in 1960 to encourage understanding between the Americans and other countries. Americorps and Vista is to help provide urgent services in rural and urban communities. this was in 1963
It measures atmospheric pressure. When the pressure is low it means it will rain/bad weather, if the pressure is high the weather will be nice/sunny out.