A freeway with two lanes, one in each direction. Super 2's are technically freeways because they are access-controlled (meaning there are no intersections, only overpasses). However, unlike most freeways, Super 2's have no medians, with only a yellow stripe dividing the lanes.
Passing is allowed on most Super 2's. Courteous drivers of slower vehicles should move over to the shoulder to let other cars get by.
Many Super 2's are on US Highways. Examples can be found all over, such as (formerly) US 1 through North Carolina, US 8 and US 51 in Wisconsin, the Daniel Boone Parkway toll road in Kentucky, and even NS 118 in Nova Scotia. New construction of Super 2's continues even today with plans for new ones in Iowa for US 65.