I had an interesting discussion with Alan Pisarski yesterday and wanted to share some of it with everyone.  Alan, along with other researchers including Dowell Myers at USC, and Evelyn Blumenburg at UCLA, have examined how time since immigration influences transit mode choice and vehicle acquisition. 


First, let’s remember that there are “standard” tables that the Census Bureau produces, and there are “custom” tables done on commission.  The 1990 and 2000 CTPP are “custom” tabulations.  The “standard” tabulations come out BEFORE any “custom” products. 


The questions on the ACS form are:


  1. Is this person a CITIZEN of the United States?
  2. When did this person come to live in the United States? Year _______


The current ACS standard products, such as profile S0502 use the specific year in the table:

Entered 2000 or later

Entered 1990 to 1999

Entered before 1990


While this approach can be useful for cohort analysis, it is less useful for understanding mode choice by time spent in the U.S.   For the CTPP2000, we had the Census Bureau create a variable called “Length of U.S. residence.”   The CTPP 2000 includes Table1-020  Length of U.S. residence by Means of Transportation to Work. 


One way to think about this is to consider “year of birth” and the variable “age.”  If a person is born in 1960, and is surveyed in 2005, their age is tabulated as 45.  If they are surveyed in 2010, their age is tabulated as 50.  If the tabulation was by “year of birth” they would always show up in the category “1960.” 


Alan wants to make sure he gets the equivalent of CTPP2000 Table 1-020 with the ACS tabulations, and have it reported for metropolitan areas, and aggregated by metro areas by population size.  So, this is an opportunity for me to bring up the topic of TABLE DESIGN for the next CTPP!  We plan for the first product of the next CTPP to use the first three years of ACS data (2005/2006/2007).  The tabulation will be limited to geographic units with population over 20,000. 


Also, Phil Salopek has already submitted a list of tables to be deleted from the ACS standard set.  This includes profile S0803, and tables of travel time by marital status, travel time by educational attainment, and travel time by household type.  He also had travel time by race and ethnicity on the list for deletions, but I asked if he could retain them as they are useful for projects on environmental justice.   IF THERE ARE SPECIFIC TABLES (particularly those related to journey to work and vehicle availability) that you MUST have as part of the ACS “standard” set, please let me know ASAP, so that we can convey this to the CB. 


If there are tables that you especially want for the first CTPP product, please convey those ideas as well.  On MY list for the first CTPP product are:

County-to-County flow tabulation (total, and by means of transportation to work)

PUMA-to-PUMA flow tabulation (total and by means of transportation to work)

However, for flow tabulations from ACS, we need to make sure that the workplace allocation program is in place to assign detailed workplace geocoding to respondents who do not supply sufficient information on their ACS form. 


Finally, for those of you who do not already know, Phil Salopek will be retiring from the U.S. Census Bureau on March 2.  He has been a great help to all of us in the transportation data community and we wish him well in his new endeavors, and we hope that he will find a way to continue to work with us!


On behalf of the CTPP Team:

Elaine Murakami