DATABASE NAME

     NTAR:  National Transportation Analysis Regions

DATABASE DESCRIPTION

     National Transportation Analysis Regions (NTARs) divide the
     U.S. into 89 areas that delineate the functional geography
     transportation demand.  NTARs are aggregates of BEA Economic
     Areas, and have been defined by the DOT for use in the 1993
     Commodity Flow Survey.

     Originally published by BTS on Transportation Data Sampler
     (BTS-CD-01)

ORIGINATING AGENCY

     Bureau of Transportation Statistics

AGENCY RESPONSIBLE FOR MAINTAINING DATA

     Bureau of Transportation Statistics

CONTACT

     National Transportation Atlas Databases
     Bureau of Transportation Statistics
     U.S. Department of Transportation
     Washington, DC  20590
     (202) 366-DATA
     Internet:  info@bts.dot

SOURCE

     Federal Highway Administration/Oak Ridge National Laboratory

ACCURACY

     Not applicable

TYPE OF GIS DATABASE

     Not a GIS database.  Table database uses county FIPS code as
     reference to GIS data.

FILES/SIZE/NUMBER OF RECORDS

     One ASCII file

     1)   ntar.tab       table file contains attributes and
                         county FIPS codes

     Approximate size of file:          152,000 bytes
     Approximate number of records:     3150

FILE STRUCTURE

     The file is ASCII-comma delimited.  Character fields are
     enclosed in quotation marks.  The first line contains header
     information

     The Table File

   FIELD  ITEM           TYPE      REMARKS

     1    FIPS           Num       County FIPS code
     2    NAME           Char      County name
     3    BEA            Num       Bureau of Economic Analysis Id
     4    BEA_NAME       Char      Bureau of Economic Analysis
                                   name
     5    NTAR           Num       NTAR Id number

DISCUSSION

     National Transportation Analysis Regions (May 8, 1991: 
     Minor revision 12/29/92)

     THE PROBLEM

     The U.S. Department of Transportation (DOT) requires
     information on the interregional movements of goods and
     people to understand the demands being placed on the
     Nation's transportation system and the ability of the system
     to meet those demands.  The required information raises two
     statistical problems:

          --   The geography of transportation demand and
          activity are molded by economic, social, and physical
          forces that generally ignore political boundaries. 
          Mountain ranges and the hinterlands of major economic
          centers are just two of the many characteristics that
          affect patterns of transportation supply and demand and
          that have little correlation to State lines.  As a
          consequence, much transportation data need to be
          organized by functional geography rather than by State
          or other political units.

          --   Data on the characteristics of activity between
          regions are inherently more massiveand thus more
          difficult to acquire and managethan data on the
          characteristics of regions.  One record per region
          becomes one record for each combination of regions. 
          For example, the individual populations of 50 States
          can be described by a column with 50 cells; the
          migrations of people from each State to each State
          needs a matrix with 2,500 cells.

     To deal with these statistical problems, the DOT needed to
     identify an effective yet parsimonious set of regions for
     measuring and analyzing nationwide patterns of
     transportation demand and activity.  The regions should have
     the following characteristics:

          --   Coverage.  The regions should cover all portions
          of the 50 States and the District of Columbia.

          --   Number.  There should be no more than 89 regions
          for some applications to keep origin-destination tables
          within 8,000 cells and because of data sample size and
          disclosure issues for the Commodity Flow Survey. 
          (Number 90 might be added later for Puerto Rico.)

          --   Functional Geography.  The regions should be based
          on centers of population or economic activity that
          account for most of the origins, destinations, or
          transfers of long distance passenger and commodity
          movements.  Each region should encompass the hinterland
          of the region's terminals for long distance
          transportation.  Where hinterlands of closely
          neighboring centers substantially overlap, the regions
          should be combined.

     (Long distance movements are generally defined by travel by
     individuals that is typically not made on a daily or weekly
     basis.  The specific length varies from 50 to 100 miles
     depending population density and door-to-door speed of the
     transportation system.)

          --   Size.  Each region should be small enough so that
          there are more long distance movements to and from
          other regions than within the region.

          --   Stability.  The regions should encompass areas of
          foreseeable growth and change so that boundaries do not
          have to be redefined within the a few years.

          --   Compatibility.  The regions should be coterminous
          withor aggregates ofregions used by other Federal
          agencies that produce statistics on transportation or
          related economic and social characteristics.

     None of the existing regional schemes used by Federal
     agencies meet all of the desired criteria:

          --   Census Regions and Divisions are far too big. 
          Most multi-State regions used by Federal agencies
          encompass more intraregional than interregional long
          distance movements, and most include  multiple, major
          centers of population and economic activity that are
          far apart.

          --   States generally do not reflect functional
          geography.  Several of the Nation's biggest population
          centers (including New York and Chicago) are divided by
          State boundaries.  Some of the biggest States also
          include multiple, major population centers that are far
          apart and should be in separate regions.

          --   BEA Economic Areas of the U.S. Bureau of Economic
          Analysis are ideal in most respects, but are too
          numerous for some applications.  Some of the 183 BEA
          areas are also too small to encompass overlapping
          transportation hinterlands (such as Baltimore and
          Washington).

          --   Metropolitan Statistical Areas (MSAs) and
          Consolidated Metropolitan Statistical Areas (CMSAs) do
          not cover the entire country and are too numerous for
          some applications.

          --   Census Production Areas used in previous Commodity
          Transportation Surveys fail on coverage and
          compatibility criteria.

          --   Labor Market Areas used by the U.S. Department of
          Agriculture are too numerous.

          --   Counties and other sub-State levels of government
          are too numerous, and most of these small areas do not
          contain major terminals for long distance
          transportation.

     BEA Economic Areas generally meet DOT's geographical
     requirements except when the number of regions becomes
     critical.  They are especially desirable building blocks for
     a less numerous set of regions since much transportation-
     related data of interest to DOT are available by BEA
     Economic Area or can be aggregated from the county level to
     BEA Economic Areas.

     THE SOLUTION

     Aggregations of BEA Economic Areas called National
     Transportation Analysis Regions (NTARs) are proposed for the
     collection and publication of transportation data when
     functional geography is preferred over political geography
     and the number of regions must be less than BEA Economic
     Areas.  Other regional definitions, such as Census
     metropolitan and urbanized areas, can be used in conjunction
     with (or instead of) NTARs when corridor-level or
     metropolitan-focused analyses are required.

     Two basic approaches are available to consolidate BEA
     Economic Areas into NTARs.  One is to start with a general
     criteria for selecting 89 areas, and then adjust the
     boundaries based on geographical judgment.  The other
     approach is to use rigid criteria to identify 89 BEA
     Economic Areas as NTAR centers and to divide the remaining
     areas among the NTARs.

     The following approach was used within the DOT to develop
     the NTARs.  BEA Economic Areas were selected as "NTAR Cores"
     based on population and surrogate measures of economic
     activity; NTAR Cores were combined where appropriate based
     on distance; and the remaining BEA Economic Areas were
     divided among the NTAR Cores based on highway distance. 
     This criteria-driven approach assumes that the major long
     distance transportation facilities of each BEA Economic Area
     are at or near the center of the areas largest major city,
     and that the hinterlands of each major long distance
     transportation facility is a function of highway distance. 
     Distance by water is substituted as needed for Alaska and
     Hawaii.

          1.   All BEA Economic Areas projected to reach
          1 million population by the year 2000 were selected as
          the initial NTAR Cores.  These 69 areas had at least
          955,000 population in 1988, and were assumed top be the
          major generators of intercity passenger travel.

          2.   All BEA Economic Areas having as many or more jobs
          as the NTAR Core with the smallest 1988 population were
          included on the list of NTAR Cores.  The NTAR Core with
          the smallest estimated 1988 population in Step 1 had
          402 thousand jobs.  This step added 11 more NTAR Cores. 
          The top 80 NTAR Cores account for approximately
          80 percent of the U.S. population and employment in
          1988, and are assumed to be the major generators of
          intercity freight movements outside of mining and
          agriculture.

          3.   An additional six ports that were not included in
          Step 2 were added as NTAR Cores.  Wilmington (NC),
          Charleston (SC), Savanna (GA), and Mobile (AL) were
          added to distinguish them from competing ports in other
          States.  Brownsville (TX) was added to distinguish it
          as a major port and Mexican gateway from other distant
          ports and border crossings in Texas.  Duluth (MN) was
          added to distinguish its Great Lakes traffic from
          Mississippi River traffic in Minneapolis.

          4.   All NTAR Cores within 50 miles of each other were
          combined.  Distance was based on the shortest major
          highway route between the centers of each area's major
          city.  This assumes that areas within such close
          proximity share major interregional transportation
          terminals.  The 50-mile criteria merged Providence into
          Boston and Washington into Baltimore, reducing the
          number of NTAR Cores to 84 and leaving room for
          5 additions.

          5.   The most distant unselected BEA Economic Area from
          the NTAR Cores was designated an NTAR Core.  Distance
          was based on the shortest major highway route between
          the centers of the major city in each area.  This step
          was repeated five times to fill out the maximum number
          of NTARs.  This step assumes that the most distant
          areas include vast domains of agriculture or natural
          resources that generate significant commodity flows,
          and that the most distant areas are so far removed that
          there are more long distance trips within the areas
          than to other NTARs.  Alaska, Great Falls (MT), Minot
          (ND), Rapid City (SD), and Boise (ID) in turn became
          NTAR Cores under this step.

          6.   Each unselected BEA Economic Area was assigned to
          the nearest NTAR Core based on the distance of the
          shortest major highway route between the centers of the
          major city in each area.

     Population and employment data used to implement these steps
     was published by BEA in Survey of Current Business,
     November, 1990, pp. 39-43.  Mileage data were calculated
     from an extraction of the ORNL National Highway Planning
     Network and the TransCAD geographic information system from
     Caliper Corporation.

     The NTARs that were designated by the DOT for use in the
     1993 Commodity Flow Survey are based initially on the above
     six steps, with the following adjustments:

          --   Reno (NV) was reassigned from Sacramento (CA),
          Yakima (WA) was reassigned from Seattle (WA) to Boise
          (ID), and Richland (WA) was reassigned from Portland
          (OR) to Boise (ID) to recognize the Sierra-Cascade
          boundary and to reduce the disparity of population and
          employment between the affected NTARs.  The boundary
          overrides distance because the mountains cause enormous
          changes in the environmentand thus the
          economybetween the Pacific Rim and the Intermontane
          West.  In the parlance of transportation surveys, the
          mountains provide an effective screen line.

          --   Minneapolis (MN) lost Sioux Falls (SD) and
          Aberdeen (SD) to Rapid City (SD), and Fargo (ND) to
          Minot (ND) to keep the grain producing regions of the
          northern Great Plains together and to provide a screen
          line between those regions and their major ports on the
          Mississippi and the Great Lakes.  These reassignments
          also provide additional population and employment to
          regions that were defined by the distance criteria and
          short on both people and jobs.

          --   Lubbock (TX) was reassigned from Dallas (TX) to El
          Paso (TX) because Lubbock is more similar in
          environment and economy to rural westernmost Texas than
          to highly urban Dallas, and because the initial Dallas
          NTAR was unnaturally elongated.

          --   Corpus Christi was assigned to Brownsville rather
          than San Antonio because the distances differed by only
          10 percent, because the economic functions and the
          environments of the two coastal areas had more in
          common with each another than with the Texas interior,
          and to reduce the disparity of population and
          employment between Brownsville and San Antonio.

          --   New Orleans (LA) picked up Shreveport (LA) from
          Dallas (TX), Lake Charles (LA) from Houston (TX), and
          Monroe (LA) from Jackson (MS) to keep the coastal and
          river ports of Louisiana together, and to provide a
          screen line between the ports and the shipping regions
          of northeast Texas, Arkansas, and Mississippi.

     The major weakness of the DOT's NTARs is that more
     differentiation of ports is desirable.  In the many cases,
     the competing ports are within the same BEA Economic Area
     and cannot be separated without cleaving the building blocks
     of the NTARs.  A five-way split of NTAR 113 along BEA
     Economic Area boundaries is also desirable to distinguish
     the river and coastal ports of Louisiana, but could not be
     accommodated without increasing the total number of NTARs or
     dramatically altering the existing NTARs.  A less drastic
     solution is to stay with NTARs and to provide separate
     tabulations as needed by port.

     The suitability of NTARs for passenger flow surveys and
     analysis is more open to question.  A modified set of NTARs
     may be proposed to support the 1995 American Travel Survey
     being carried out by the Bureau of the Census and Bureau of
     Transportation Statistics.