In the 1970s, the population of Le Sueur City was around 4,000. The city underwent moderate growth. In 1980, its population was projected to grow to over 4,800. The city's comprehensive plan recommended street patterns, residential neighbourhoods, and park locations. The area's economy was heavy in agriculture, although manufacturing and service industries were beginning to grow. The city was referred to as a "farm trade and employment center."
Le Sueur City's population is slightly older than the statewide average. The ratio of males to females is largely similar. Two-thirds of the city's residents have at least a high school diploma, while one-third have only an associate's degree. The city's percentage of residents who are under age 20 is nearly the same as statewide, while its percentage of residents who are over age 65 is slightly lower.
The city is also home to a large industrial sector, including auto manufacturing, and other manufacturing operations. These industries generate large amounts of vehicular traffic, and the density of these buildings requires greater visibility on major roads. While industrial areas are often located near downtown, recent development has extended further north along Highway 169.
The city has a varied population, with the median age of 37.9. The average household size was 2.97 persons. Twenty-five percent of the city's residents were under the age of 18, while 7.8% were between the ages of 18 and 24. Almost forty percent of households were headed by married couples. A further twenty-five percent were headed by individuals. Only one-seven percent of households were headed by a senior citizen, and one-tenth were headed by a child.