Importing x,y data into ArcGIS

Importing a set of x,y coordinate pairs into ArcGIS is very straightforward, and can be a

useful skill if you need to bring in simple coordinate data that is not already in a spatial format.

1) Acquire some data you want to display on a map. The source doesn’t matter: it might be

locations recorded on a GPS unit that you don’t have a data cable for, coordinates determined

from a topographic map, or a simple data set found on the internet. If you want your locations

to integrate correctly with other layers (always a good thing in GIS) you will need to know

both the coordinate system and datum used by the source data, e.g. latitude / longitude and

NAD27.

2) Format your data properly. This may be done in a spreadsheet program such as Google

Spreadsheets <spreadsheets.google.com>, or the more ubiquitous Excel. To import properly

into ArcGIS, your data file will require a minimum of three fields: a unique identifier for each

data point, and the X (easting) and Y (northing) for each location. Other attribute data, if

available, may go into additional columns, but your points will import fine with just these

three pieces of information. Your file should also contain a header line that describes each

field. It might be as simple as ID, X_coord, Y_coord. Additional fields are OK, but

descriptions in each header are limited to seven characters and cannot have special characters

or spaces. If you need spacing for readability, use underscores.

Be sure if you are using latitude/longitude coordinates that

your northings are positive ifnorth of the equator and eastings are negative if you are in

the western hemisphere. Example: the coordinates for a location in Houghton, Michigan are -

88.54820, 47.11535 inlatitude/longitude and 382552, 5219145 in UTM zone 16, NAD 1983

datum. Omitting the “-” sign will put your points on the wrong side of the globe.

If your coordinates are in latitude/longitude, they should be in decimal degrees (DD) format

before importing into ArcGIS. Locations in degrees, minutes and seconds (DMS) or decimal

minutes (DM) format should first be converted to DD. There are converters available on the

internet, but it is probably quicker to use Excel to perform the conversion.

D = Degrees M = Minutes S = Seconds .m = Decimal Minutes .s = Decimal Seconds

DM.m = Degrees, Minutes, Decimal Minutes (eg. 45°22.6333)

D.d = Degrees, Decimal Degrees (eg. 45.3772°)

DMS = Degrees, Minutes, Seconds (eg. 45°22’38″)

DMS –> DM.m (45°22’38″ –> 45°22.6333)

◦ Divide S by 60 to get .m (38/60=.6333)

◦ Add .m to M to get M.m (22+.6333=22.6333)

DM.m –> D.d (45° 22.6333 –> 45.3772)

◦ Divide M.m by 60 to get .d (22.6333/60=.3772)

◦ Add .d to D to get D.d (45+.3772=45.3772)

D.d –> DM.m (45.3772 –> 45°22.6333

◦ Multiply .d by 60 to get M.m (.3772*60=22.6333)

DM.m –> DMS (45°22.6333 –> 45°22’38″)

◦ Multiply .m by 60 to get S(.6333*60=38)

DMS–>DD

◦ D + M/60 + S/3600 = DD

3) Save/export your data as a comma-delimited text file (CSV format in Google Spreadsheets

or Excel). You may want to save a copy in native format (.xls in both Google spreadsheets

and Excel) before exporting to .csv.

4) Add your .csv file to ArcMap by using the Add data tool (either by expanding the

submenu under File> Add Data) or by clicking the

Add Data tool on the Standard toolbar

5) Right-click on your new layer and choose Display XY Data… Ensure that the X and Y

fields were selected correctly by ArcMap – they should be right if you chose names that

reflect the coordinate positions (northing and easting or x and y). Click the Edit… button,

then Select… to select the coordinate system for your points, Add… and OK (3x). The

correct coordinate system to use may be obtained from your GPS unit (under map setup or

units); from the marginal information on your topo map; or from the metadata file that came

with internet data. Look in geographic coordinate systems for latitude/longitude projection

files, or in projected coordinate systems > UTM for UTM data.

Some possible suggestions:

Coordinate Systems > Geographic Coordinate Systems > World >

WGS1984.prj (default GPS datum)

Coordinate Systems > Geographic Coordinate Systems > North America >

NAD1983.prj (current North American datum)

Coordinate Systems > Projected Coordinate Systems > UTM > NAD1983 > NAD

1983 UTM Zone 16N.prj (appropriate for most of the U.P.)

Coordinate Systems > Projected Coordinate Systems > State Systems > NAD 1983

Michigan GeoRef (Meters).prj (projection and datum used by the State of Michigan)

6) You should now have a point layer at the top of your Table of Contents with the same

name as your .csv file and the word Events on the end of the name.

This is an “event theme” and is a temporary layer. If you want a more permanent copy, right-

click on the layer and choose Data > Export Data… Pick an output location—a geodatabase

feature class or a directory for a shapefile—and enter a file name. Please change the name to

something other than the default Export_Output – I suggest one that more accurately reflects

the contents of the data layer. Click OK.

You now have a permanent layer, either a geodatabase feature class or shapefile, of your

original ASCII (text) coordinates.