This policy has been superseded and is no longer in effect.

                    STATE PLANE COORDINATE SYSTEM OF 1983
                    January 1991


The State Plane Coordinate System of 1927 was published in a unit
of measure identified as the "U.S. Survey Foot." By 1959, except
for surveying and mapping applications, the United States had
switched to the unit of measure identified as the "International
Foot." A Federal Register Notice published in 1959 (24 FR 5348)
stated that the surveying and mapping profession could continue
using the U.S. Survey Foot until such time that the national
network of horizontal control was readjusted, after which the
International Foot should be used. However, in 1989 the Federal
Geodetic Control Committee, in order to accommodate the prefer-
ence of the majority of its member organizations, officially
adopted the U.S. Survey Foot for federally funded projects.

In preparation for the adjustment of the North American Datum
of 1983, 31 states enacted legislation for the State Plane
Coordinate System of 1983 (SPCS 83). All states defined SPCS 83
with metric parameters. Within the legislation, the U.S.
Survey Foot was specified in 11 states and the International
Foot was specified in 6 states. In all other states the meter
is the only referenced unit of measure in the SPCS 83 legisla-
tion. The remaining 19 states do not yet have any legislation
concerning SPCS 83.

From 1977 until the present, NGS has maintained the meter as
the official unit of measure for SPCS 83 and the unit on which
plane coordinates would be based within NGS published data
(42 FR 15943). In 1986 NGS supplemented this position with
publication of a notice that, on request, surveyors could obtain
SPCS 83 coordinates from NGS in the foot unit legislated by the
state in which the survey station resides.

Last year the U.S. Geological Survey (USGS) sent letters to all
states regarding which SPCS 83 units should be shown on their map
products. These letters said in part:

    "The National Mapping Division (NMD) is implementing procedures
    that will result in using or referencing the North American
    Datum of 1983 (HAD 83) for all new and replacement maps. One
    important aspect of these implementation plans is the
    determination of how to label the State Plane Coordinate
    System (SPCS) on these graphic products. The HMD has an
    immediate need to resolve this issue so that automatic base
    sheet plotting software can be developed or modified to
    produce SPCS ticks and labels conforming with the
    requirements of the states."


The surveying and mapping community continues to use the foot
despite Federal efforts toward metrification. In addition, the
proliferation of computerized land information systems (LIS) is
increasing the use of the foot unit. Because SPCS 83 is
presently published by NGS only in meters, many surveyors,
mappers, engineers, and LIS users are converting these metric
values to feet. In most instances they are performing the
conversion correctly, using the correct conversion factor and
the proper number of significant digits. However, there have
been instances where the conversions were done using the wrong
conversion factor or the computation was otherwise done
incorrectly. Finally, in some states USGS' NMD will be showing
SPCS 83 tick marks in feet on its maps. Federal surveying and
mapping agencies should be consistent in their products to the
extent practical.

To better serve users and lessen the potential for costly
mistakes, NGS has adopted the following policy.


If the following criteria are met, NGS will publish future
SPCS 83 values in both meters and feet for the specific state:

l.   The appropriate state contact, speaking for the majority of
     the state surveying and mapping community (both public
     agencies and professional societies), requests in writing
     that NGS publish both meters and feet.

2.   The request to NGS is consistent with the state's recommen-
     dation to USGS for use in the state/USGS cooperative mapping

3.   The state has enacted SPCS 83 legislation that specifically
     defines the conversion factor (for either the U.S. Survey
     Foot or International Foot) to be used.

Until all three items listed above are resolved for a particular
state, NGS will continue to publish SPCS 83 values only in
meters for that state.


The original (present) NAD 83 coordinate listings (covering
1x2-degree areas) will continue to be printed and distributed
showing only meters, as will the existing NAD 83 Horizontal
Control Data sheets.

NGS will publish both meters and feet as specified in this
POLICY STATEMENT only on its new "unified" geodetic control data
sheet. This new sheet provides a single publication format for
all geodetic control in NGS' data base, including horizontal,
vertical, and gravity values.

Status of 1927 and 1983 State Plane Coordinate System (SPCS)
Status of NGS Publication of SPCS 83 Values in Feet

National Geodetic Survey
January 1991