A single-member district (single-member constituency) is an electoral district that sends one officeholder to a body. In America, state legislatures and the united state congress are both elected from single-member districts.
In the United States, single member district has been used to elect across all levels i.e. local, state and federal because it makes sure that communities which are small in size and population are represented in legislative assemblies.
The clouds of hot ash was on its way to New England but the deadly gases it kept on collecting was making it slower and slower to get it to its "destination".