Finding, downloading, and processing NHGIS data can sometimes be challenging given the many complexities of historical census data and GIS software. The guides here are designed to help new users through the most common tasks and obstacles. They should also be useful for experienced NHGIS users who are not yet familiar with the new data extraction system.
This user's guide covers the entire process of selecting and downloading NHGIS data. Users are walked through two scenarios of differing complexity and learn how to use filters to find the tabular data and GIS boundary files they seek.
Data tables downloaded from NHGIS are not automatically included within NHGIS boundary files. Users must complete a 'Join' operation inside GIS software to attach the tabular data to the boundary files before mapping or spatially analyzing the census information. This guide walks users through the steps of completing the 'Join'.
With the new NHGIS data extraction system, users no longer specify a particular area they wish to download data for, but instead receive data for the entire country (or state when working at the block or block group level). For example, if interested in data for Hennepin County, Minnesota, you need no longer select Minnesota and then Hennepin County. Instead, you simply download county-level data for the entire United States. This tutorial guides users through the different methods of isolating specific locations in Esri ArcGIS so they can be mapped and analyzed independently even when data files cover a larger geographic extent.
Unfortunately, when adding a .csv file into Esri ArcGIS 8.x, 9.x or 10.0 through standard operations, the maximum number of columns that ArcGIS will import is 255, and any additional fields are truncated. Given that NHGIS data requests frequently exceed this limit, many users need to be able to get around this issue. Two work-arounds are discussed in this document. Please note that Esri ArcGIS 10.1 has rectfied this issue, allowing more than 255 column .csv files to open correctly.