[Woodward Avenue north from Opera House corner, Detroit, Mich.]

Detroit was the Silicon Valley of the late 19th and the first half of 20th century. The city grew into a hub of commerce and industry spread along Jefferson Avenue, with multiple manufacturing firms taking advantage of the transportation resources afforded by the river and a parallel rail line. Around the start of the 20th century, numerous entrepreneurs in the Detroit area forged into a production of the automobile, capitalizing on the already-existing machine tool and coach-building industry in the city. A thriving trade set the stage for the work of Henry Ford, whose automobile Highland Park Ford Plant in 1910 revolutionized not only automobile manufacturing but virtually created the concept the assembly line and mass production. Historic Gilded Age gave rise to upscale neighborhoods, including the Boston-Edison, Indian Village, and Palmer Woods. In 1930s, with the factories came high-profile labor unions. The labor activism during those years increased the influence of union leaders in the city such as Jimmy Hoffa of the Teamsters and Walter Reuther of the Autoworkers. The city became the 4th-largest in the nation in 1920, after only New York City, Chicago and Philadelphia, with the influence of the booming auto industry. The Great Depression was devastating for Detroit, as sales of automobiles plunged and there were large-scale layoffs at all industrial enterprises. Major Murphy insisted that no one would go hungry, and set up the Mayor's Unemployment Committee that set up relief soup kitchens and potato gardens. From 1942 to 1945, production of commercial automobiles in the city ceased entirely, as its factories were used instead to construct M5 tanks, jeeps, and B-24 bombers for the Allies. By 1945, Detroit was running out of space for new factories. The postwar years 1945-70 brought high levels of prosperity as the automobile industry had its most prosperous quarter-century. Detroit, like many places in the United States, developed racial conflict and discrimination following rapid demographic changes as hundreds of thousands of workers were attracted to the industrial city. In the 1970s and 1980s dozens of violent street gangs gained control of the city's large drug trade, which began with the heroin epidemic of the 1970s when the crimes became increasingly more destructive. Hundreds of vacant homes across the city were set ablaze by arsonists. The number of fires was reduced only by razing thousands of abandoned houses - 5,000 in 1989-90 alone. In the late 1980s and early 1990s, the city began to experience a revival, much of it centered in Downtown, Midtown, and New Center.

The history of trams, streetcars or trolleys began in the early nineteenth century. The world's first horse-drawn passenger tramway started operating in 1807, it was the Swansea and Mumbles Railway, in Wales, UK. It was switching to steam in 1877, and then, in 1929, by very large (106-seats) electric tramcars, until closure in 1961. Horse Cars The first streetcar in America, developed by John Stephenson, began service in the year 1832 in New York. Harlem Railroad's Fourth Avenue Line ran along the Bowery and Fourth Avenue in New York City. These trams were a horse- or mule-powered, usually two as a team. It was followed in 1835 by New Orleans, Louisiana, which is the oldest continuously operating street railway system in the world, according to the American Society of Mechanical Engineers. Horsecars were largely replaced by electric-powered trams following the improvement of an overhead trolley system on trams for collecting electricity from overhead wires by Frank J. Sprague. Sprague spring-loaded trolley pole used a wheel to travel along the wire. In late 1887 and early 1888, using his trolley system, Sprague installed the first successful large electric street railway system in Richmond, Virginia. By 1889, 110 electric railways incorporating Sprague's equipment had been begun or planned on several continents. Steam Cars Trams were also powered by steam. The most common type had a small steam locomotive (called a tram engine in the UK) at the head of a line of one or more carriages, similar to a small train. Systems with such steam trams included Christchurch, New Zealand; Adelaide, South Australia; Sydney, Australia and other city systems in New South Wales; Munich, Germany (from August 1883 on), British India (Pakistan) (from 1885) and the Dublin & Blessington Steam Tramway (from 1888) in Ireland. Steam tramways also were used on the suburban tramway lines around Milan and Padua; the last Gamba de Legn ("Peg-Leg") tramway ran on the Milan-Magenta-Castano Primo route in late 1958. The other style of steam tram had the steam engine in the body of the tram, referred to as a tram engine (UK) or steam dummy (US). The most notable system to adopt such trams was in Paris. French-designed steam trams also operated in Rockhampton, in the Australian state of Queensland between 1909 and 1939. Stockholm, Sweden, had a steam tram line at the island of Södermalm between 1887 and 1901. Steam tram engines faded out around 1890s to 1900s, being replaced by electric trams. Cable Cars Another system for trams was the cable car, which was pulled along a fixed track by a moving steel cable. The power to move the cable was normally provided at a "powerhouse" site a distance away from the actual vehicle. The London and Blackwall Railway, which opened for passengers in east London, England, in 1840 used such a system. The first practical cable car line was tested in San Francisco, in 1873. Part of its success is attributed to the development of an effective and reliable cable grip mechanism, to grab and release the moving cable without damage. The second city to operate cable trams was Dunedin in New Zealand, from 1881 to 1957. The San Francisco cable cars, though significantly reduced in number, continue to perform a regular transportation function, in addition to being a well-known tourist attraction. A single cable line also survives in Wellington, New Zealand (rebuilt in 1979 as a funicular but still called the "Wellington Cable Car"). Another system, actually two separate cable lines with a shared power station in the middle, operates from the Welsh town of Llandudno up to the top of the Great Orme hill in North Wales, UK. As with all large collections on Picryl, this collection is made in two steps - first, we make a manual dataset, and then, ran 25+ Million public domain images through our neural network image recognition process.