I & M Canal survey maps

Eastern portion of the Post and Paul canal survey map of 1824. This map was submitted to President Monroe to be the basis for the construction of the canal, in accordance with the federal Act of 1822. However, the map was misplaced and the canal was not begun before the Act of 1822 expired.

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Thompson canal survey map of 1829, which followed the federal Act of 1827. As part of the new law, the federal government donated half the width of five sections of land on either side of the proposed canal to the state. The reason for the land grant was to make canal construction affordable to the young state of Illinois. The placement of the the I & M Canal is based in a rough way on this map. However, the route does not quite follow it. Thompson was also responsible for platting the Original Town of Chicago in 1830.

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Part of a Retrospective map of the Canal Land Grants (1956), showing canal lands in Cook county. As part of the land grant, the "half" that was given to the state consisted of alternating sections. The canal commissioners, having the option, chose the odd numbered sections, giving the commissioners control of the forks at both Chicago and Bridgeport. Note that the peculiar way in which the sections of each township are numbered allow for this possibility. Section numbering begins with 1 on the top row of each Township and increases moving east. But the next row of sections is counted moving the reverse direction (west), the next row after counts moving east again and so on until number 36 is reached on the bottom -- often refered to as a serpentine scheme. Not all 36 numbers apply to every township here, since those near the lake are not a full (six mile) square; such townships are termed fractional townships.

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Retrospective map (1956), summarizing the various principal surveys of the potential Illinois & Michigan Canal routes near Bridgeport. Several surveys were made, not only for the purpose of locating the canal route, but also to comply with the laws authorizing the canal in the first place. The variance in the routes shown on this map illustrate well the difference between legislating and planning the canal as opposed to actually building it.

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Source: Walter A. Howe, compiler, Division of Waterways, Documentary History of the Illinois and Michigan Canal: legislation, litigation, and titles (Springfield: State of Illinois, 1956).

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