U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
583 zones are planned for the national passenger travel origin destination (OD) data as illustrated in Figure 1.
Figure 1 – Planned Passenger Travel Origin Destination Zone Illustration.
These 583 zones include: a) 137 new zones created from counties of reminders of States and b) 446 MSA based zones divided into state specific MSAs for these multistate MSA zones (Figure 2).
Figure 2 – Multistate MSA Zone Divides by State Boundaries Illustration.
Among the 446 new MSA zones, 16 MSA zones are modified by 17 isolated rural or MiSA counties to avoid such isolated counties be combined with none geographically connected reminder of state zones. Table 1 shows these counties and the adjacent MSA zones in which they consolidated.
Table 1 – Rural or Micropolitan Statistical Area Counties Merged into Adjacent MSAs.
|County Name||State||County FIPS||State FIPS||CBSAFP Merged Into||CBSAFP2 Abb|
|La Paz||AZ||12||4||4974||49740 AZ|
|Santa Cruz||AZ||23||4||4906||49060 AZ|
|St. Mary||LA||101||22||2638||26380 LA|
|Los Alamos||NM||28||35||1074||10740 NM|
Process Used in Creating the 583 Zones
Below briefly describes the process used to establish the planned passenger travel origin destination zones.
The U.S. Census high resolution (1:500k scale) county cartographic boundary shapefiles (2017_us_county_500k) is downloaded from the weblink (https://www.census.gov/geo/maps-data/data/cbf/cbf_counties.html) and opened as a layer in GIS.
Figure 3 – Location of Cartographic Boundary Shapefiles.
The 2017 U.S. Census Core Based Statistical Area cartographic data high resolution (1:500k scale) (cb_2017_us_cbsa_500k) file is downloaded from https://www.census.gov/geo/maps-data/data/cbf/cbf_msa.html (Cartographic Boundary Shapefiles – Metropolitan and Micropolitan Statistical Areas and Related Statistical Areas) and is overlaid under the “county” layer.
Figure 4 – 2017 U.S. Census Core Based Statistical Area cartographic data high resolution file.
MSA attributes from the Statistical Area layer are transferred to the correct County or County Equivalent layer as additional county level attributes. Upon completion of this step, each county or county equivalent has the MSA attributes. For these counties or county equivalents which are rural (not an MSA or MiSA), the corresponding attribute fields are blank.
Rural or Micropolitan Statistical Area (MiSA) counties or county equivalents in each state are manually assigned new codes grouping such adjacent and contiguous counties together as remainders of state zones. Depending on each state, the number of remainders of state zones can be none to several.
The naming convention for remainders of a state is R + state name abbreviation + a numeral. For example, RTX1 stands for: this zone is a reminder (R) zone in the state of Texas (TX) and coded as zone 1. Where RTX2 stands for the other reminder zone located in the state of Texas (TX) and coded as zone 2. All remainder zones start with the letter R.
The modified high-resolution county boundary file has the following attributes:
|CBSAFP2:||Core Based Statistical Area Federal Code + remainder of state codes|
|CBSA:||Core Based Statistical Area Name|
|LSAD:||The legal/statistical area name description|
|Not_MSA-But:||This field identifies whether a rural or MiSA county is combined into an adjacent MSA or not. When there is no entry to the field, it means the corresponding “county” is not merged. If there is an entry, it means the corresponding “county” is merged into a CBSAFP2 zone.|
|County:||County legal name|
|County_FIPS:||County FIPS code|
|State_Abb:||Current state name abbreviation|
|STATEFP:||Current state FIPS|
|CBSAFP2_State:||Combination of CBSAFP2 and State_Abb. This field is the prime ID for the planned passenger travel origin destination zone.|
A new OD zone boundary file based on the modified high resolution county cartographical data obtained in Step 4 is generated in GIS by using the CBSAFP2_State attribute as the grouping parameter.
The newly created OD zone boundary file has the following attributes:
|CBSAFP2_ST:||Planned passenger travel origin destination zone ID|
|CBSAFP2:||IDs for MSA (identical to the original Census MSA IDs) and reminders of states (FHWA created)|
|CBSA:||Core based MSA name (identical to the original Census MSA names)|
|State_Abb:||Abbreviation of state names.|
There are two sets of geospatial boundary datasets created. The first set is the enhanced high resolution county boundary file where county attributes also include the passenger OD zone identifier. The second is the planned passenger OD zone geospatial boundary file.
Enhanced County Geospatial Boundary Dataset
Planned Passenger Travel OD Geospatial Zone Dataset