the congress hotel in chicago was built at grant park in chicago.
when was the congress hotel in chicago built?
grant park in chicago
the first application for balanced lines was for telephone lines. interference that was of little consequence on a telegraph system (which is in essence digital) could be very disturbing for a telephone user. the initial format was to take two single-wire unbalanced telegraph lines and use them as a pair. this proved insufficient, however, with the growth of electric power transmission which tended to use the same routes. a telephone line running alongside a power line for many miles will inevitably have more interference induced in one leg than the other since one of them will be nearer to the power line. this issue was addressed by swapping the positions of the two legs every few hundred yards with a cross-over, thus ensuring that both legs had equal interference induced and allowing common-mode rejection to do its work. as the telephone system grew, it became preferable to use cable rather than open wires to save space, and also to avoid poor performance during bad weather. the cable construction used for balanced telephone cables was twisted pair; however, this did not become widespread until repeater amplifiers became available. for an unamplified telephone line, a twisted pair cable could only manage a maximum distance of 30 km. open wires, on the other hand, with their lower capacitance, had been used for enormous distances—the longest was the 1500 km from new york to chicago built in 1893. loading coils were used to improve the distance achievable with cable but the problem was not finally overcome until amplifiers started to be installed in 1912. twisted pair balanced lines are still widely used for local loops, the lines that connect each subscriber's premises to their respective exchange.
balanced line
through the 1930s the hotel was run by hotel industry pioneer ralph hitz's national hotel management company. at this same time, part of the hotel was used as the location for a benny goodman nbc radio show. following the outbreak of world war ii, the government purchased the congress hotel and used it as a training school for u.s. army air forces.





























it reopened for civilian use in time for the summer political conventions of 1944. at this time, john j. mack was president of the michigan-congress hotel corporation.
congress plaza hotel