The Vietnam War! The p<span>eople demanded a change in the voting age because of </span><span>the Vietnam War.</span><span> The US government was drafting 18 year old men to fight, and in the w</span>ar, but before 1971, some 18 year olds in the US did not have the right to vote. After the US passed the 26th Amendment, all states had to allow 18 year old citizens to vote.
Constantine issued the Edict of Milan.
Workers in factories did not have to work around in daylight. Additionally, workers in factories faced hazardous conditions with many more individuals than farm work.
Coal and wood are two sources which had been used extensively since the 18th century. when steel was commercialized heavily using the Bessemer Proces later at the 19th century. At this time, petroleum became the major energy source of energy and was even used extensilvely in other processes as converting petroleum to fuels.