Sentence:  In the late 1950s and 1960s most large cities started planning <WSD>freeway</WSD> systems, acknowledging the incredible growth in car ownership. 
Meaning of the word marked with <WSD> tags:  A road designed for safe, high-speed operation of motor vehicles through the elimination of at-grade intersections, usually divided and having at least two lanes in each direction; a dual carriageway with no at-grade crossings, a motorway.