In the 19th century Markham had a vibrant, independent community with mills, distilleries and breweries around the Highway 7 and 48 intersection. The Thomas Speight Wagon Works exported products (wagons, horsecars) around the world, and Markham had a reputation as being more active than York (the former name for Toronto) early on. Most of these industries disappeared leaving farming as the main source of business.
Light industries and businesses began to move into Markham in the 1980s attracted by land and lower taxes. Today, it claims to be "Canada's Hi-Tech Capital" with a number of key companies in the area, such as IBM, Motorola, Toshiba, Lucent, Honeywell, Apple, Genesis Microchip, and is home to the head office of graphics card producer ATI (recently merged with AMD).
Markham also maintains economic and cultural cooperation agreements with the city of Laval, Quebec, which is the second largest city in the Greater Montreal area.