For various reasons banks find it desirable to carry balances with other banks. The primary reason for such balances is that of keeping themselves in position to furnish their customers with exchange. X, for instance, who is a customer of bank B in San Francisco, may find it necessary from time to time to pay his debts in New York funds, which means that he occasionally wants a check which is payable in New York. He obtains this by asking his bank to draw in his favor or in favor of a designated concern upon the balance which it is carrying with the New York bank. This makes it desirable for the country bank to have a sufficient balance in New York - and of course at other points in case it has to draw upon them. When such relations exist between banks one is said to be the correspondent of the other, and such correspondents frequently undertake various duties. These duties may be of a more or less elaborate character or they may be comparatively few in number. The country correspondent of a city bank usually does nothing for that bank except to collect funds, remit them, and possibly carry a balance in its favor. The city correspondent for a country bank does the same kind of work, but is ordinarily called upon to carry a larger balance and to allow interest upon it. From time to time it may be allowed to invest this balance or a part thereof, passing upon the securities or notes that are taken and thus morally guaranteeing their goodness. Conversely, it may be asked to convert such securities or notes into cash through repurchase or rediscount. It may also be asked to open foreign credits on behalf of the country bank and to transact various other kinds of business. The city bank usually supplies its correspondent information from its credit files, and the latter may be occasionally requested by the city bank to supply information regarding some individual or concern in its own immediate neighborhood as to which the city bank wishes to be informed.