City merchants once considered traffic congestion to be the greatest hindrance to their success. Some of the problem came from cars randomly parked, impeding the flow of traffic. Parking meters seemed to solve that problem and provide some much needed income for growing metropolitan areas. By the middle of the 20th century, cities were taking in $10 million from parking meters. That income has increased, but so have the inconveniences. Not only do drivers have to "feed" the meters on a regular basis, they have to time their visits in order to stay within posted limits. As annoying as this is, a city parking violation has worse consequences. It can cost between $25 and $250. Late fees can increase or even double the fines. In addition, serious delinquency can lead to "booting," a hold on the owner's registration, or towing.