Net Outmigration from Puerto Rico Slows During Pandemic

Starting this year, the Census Bureau began using Airline Passenger Traffic (APT) data from the Bureau of Transportation Statistics (BTS) to directly measure net migration to and from Puerto Rico and the rest of the world.

The previous methodology estimated migration flows from Puerto Rico to the mainland United States based on responses to the American Community Survey (ACS) residence one year ago (ROYA) question, which asks where respondents lived one year prior to the survey.

Conversely, migration flows from the United States to Puerto Rico were obtained from the Puerto Rico Community Survey (PRCS) ROYA question. The net migration estimate was derived from subtracting the in- and out-migration flows.

ACS/PRCS data are collected on a continuous basis throughout the calendar year, though movement could have occurred at any time over a two-year period, depending on when the respondent was included in the sample and when they actually moved.

In the United States, flight data are compiled from monthly reports filed by over 200 commercial U.S. and foreign air carriers with BTS, including both domestic and international flights.

Data are reported for all flights following federal reporting guidelines that went into effect in October 2002. APT data include information on all travelers, without differentiation of passenger type. It includes tourists and visitors who make up the majority of passengers.

Nonmigrants are counted on both inbound and outbound flights. Migrants are only counted in one direction unless leaving temporarily, in which case they would be counted again upon their return.

However, there are limitations to this method.

For example, it can only provide a number for “net” migration, with no information on total in- or out-flows. Migrants cannot be distinguished from the total number of passengers entering or leaving Puerto Rico.

Another limitation is that no demographic characteristics of net migrants are included in the data. Additionally, this method only applies to a country or territory without any land borders, such as islands like Puerto Rico, where airplane travel is the predominant method of arriving or leaving. Ship passenger movement to and from Puerto Rico is assumed to be minimal.

Monthly tallies of net airline passenger flow movement reflect seasonal variation related to tourism, with presumably greater movement into and out of Puerto Rico in the summer and winter vacation months.

Depending on the measurement period, such as a calendar year, this could lead to year-to-year fluctuations related to annual tourism trends.

For example, a high number of tourists could be counted in December, while the return of these same tourists might occur in January of the following year. Over time, these fluctuations are thought to balance out.

Annual net migration totals are calculated using in/out passenger flow data for the 2021 estimates year based on Airline Passenger Traffic data: Inbound total passengers to Puerto Rico are subtracted from outbound total passengers from Puerto Rico.

This method includes international passengers. Typically, domestic flight data are received with a three-month lag, while international data are available six months later.

However, the Census Bureau has an internal agreement with the Bureau of Transportation Statistics to access international data with only a three-month lag, enabling us to include current international flights in our estimates. 

There are several advantages to using a flight-based methodology over the former survey-based methodology:

• Flight data can provide up-to-date estimates for the period we want to estimate.
• Flight data include movement between Puerto Rico and the rest of the world, while the former methodology only included movement from Puerto Rico to/from the United States.
• The period covered by flight data aligns with the July 1-June 30 estimates year while the ACS and PRCS cover the January-December calendar year.