Over the years, the city has been home to other large corporations in the central United States, making Denver a key trade point for the country. Several well-known companies originated in or have relocated to Denver. William Ainsworth opened the Denver Instrument Company in 1895 to make analytical balances for gold assayers. Its factory is now in Arvada. AIMCO (NYSE: AIV)—the largest owner and operator of apartment communities in the United States, with approximately 870 communities comprising nearly 136,000 units in 44 states—is headquartered in Denver, employing approximately 3,500 people. Also Samsonite Corp., the world's largest luggage manufacturer, began in Denver in 1910 as Shwayder Trunk Manufacturing Company, but Samsonite closed its NE Denver factory in 2001, and moved its headquarters to Massachusetts after a change of ownership in 2006. The Mountain States Telephone & Telegraph Company, founded in Denver in 1911, is now a part of telecommunications giant CenturyLink.
A highway expansion and transit project for the southern I-25 corridor, dubbed T-REX (Transportation Expansion Project), was completed on November 17, 2006. The project installed wider and additional highway lanes, and improved highway access and drainage. The project also includes a light rail line that traverses from downtown to the south end of the metro area at Lincoln Avenue. The project spanned almost 19 miles (31 km) along the highway with an additional line traveling parallel to part of I-225, stopping just short of Parker Road.
Most of Denver has a straightforward street grid oriented to the four cardinal directions. Blocks are usually identified in hundreds from the median streets, identified as "00", which are Broadway (the east–west median, running north–south) and Ellsworth Avenue (the north–south median, running east–west). Colfax Avenue, a major east–west artery through Denver, is 15 blocks (1500) north of the median. Avenues north of Ellsworth are numbered (with the exception of Colfax Avenue and several others, such as Martin Luther King, Jr. Blvd and Montview Blvd.), while avenues south of Ellsworth are named.
State Highway 470 (C-470, SH 470) is the southwestern portion of the Denver metro area's beltway. Originally planned as Interstate 470 in the 1960s, the beltway project was attacked on environmental impact grounds and the interstate beltway was never built. The portion of "Interstate 470" built as a state highway is the present-day SH 470, which is a freeway for its entire length.