Public works are a big part of overall city operations in terms of budget, customer service, number of employees, projects, and essential functions. Donald C. Stone, the founder of the American Public Works Association (APWA), defined public works thusly:

Public works are the physical structures and facilities that are developed or acquired by public agencies to house governmental functions and provide water, power, waste disposal, transportation, and similar services. So, public works departments exist to build, operate, and maintain infrastructure and provide services that benefit the public. The APWA has identified 145 different functions that are related to public works. They can be classified into 8 broad categories.

• Transportation. This includes streets, bridges, sidewalks, bike paths, airports, seaports, traffic control, and storm water management. Public works is responsible for the design, construction, and maintenance of these facilities.
• Sanitation. Traditionally cities collect solid waste, brush, leaves, and bulky items within the corporate limits. Cities, counties, or private companies may own disposal facilities such as landfills, compost facilities, and incinerators. Also, many cities are involved in recycling operations.
• Utilities. This includes water, wastewater, gas, and electric. It may also include cable TV service, internet service, storm water and flood control. Utility operations may be a function of public works or other city departments; other governmental entities or private companies may handle utilities.
• Buildings and grounds. This includes the design, construction, maintenance, and management of public buildings and facilities. It may include urban forestry.
• Municipal engineering. This includes civil and environmental engineering functions such as new facilities design, technical studies, construction inspection, and surveying. Larger departments tend to perform some of their own engineering services; small departments will contract these services. Major and complex projects are almost always contracted.
• Fleet management. This function involves the procurement and maintenance of city-owned equipment and vehicles. Some public works departments manage only their own equipment; some provide this service for all city departments. Many cities (departments) contract maintenance services.
• Management and administration. This includes operations management and supervision, financial management and reporting, public relations, procurement of professional services, requesting and evaluating proposals, awarding bids and managing contracts.
• Other. Various other functions such as parks maintenance, cemetery operation, airport services, animal control, dead animal pickup, etc. may be included under public works.