Photographic paper reacts to light to produce the image taken by a camera and stored on film. Darkrooms used red lighting to allow photographers to control light carefully, so that light-sensitive photographic paper would not become overexposed and ruin the pictures during the developing process.
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We could say that the growth of the cotton industry and the expansion of slavery into new states such as Alabama and Mississippi this ended hope's for a very gradual end to slavery so its opponents had the necessity to stop it from spreading to the new lands of the Louisiana Purchase. However, by the year of 1818 the northern states had a majority of growing immigrants in the House.
The correct answer is Cotton.
Texas was a great area for cotton because of the vast amounts of land that were farmed and because of the amazing climate. They also had slaves so they could have them work on those farms and produce cotton which was the main thing in their economy.