Boston City Councilor Liz Breadon, who inherited oversight of the city’s redistricting process last month in the wake of Ricardo Arroyo's temporary chairmanship suspension, has filed an order demanding data from the Boston Planning and Development Agency to help shape the process of redrawing the city’s district lines.

The subpoena, dated for the council’s next meeting on Sept. 14, will trigger a weeklong countdown for Mayor Michelle Wu to deliver several data sets from the BPDA.

Of the data demands, Boston’s total population by race and ethnicity and Boston’s voting age population organized according to race and ethnicity are two factors that play an inevitably large part in determining how district lines are adjusted.

“The Boston Planning and Development Agency in its capacity as the planning board for the city of Boston has, historically, provided census data interpretation and community profiles that have informed previous redistricting efforts,” Breadon said in an interview with GBH News Monday. “The information we’re particularly interested in is the total change between the 2010 population and the 2020 census.”

Breadon’s formal data request, which she described as a non-hostile one, comes as the November deadline for new city council district maps draws closer amid a confluence of factors.

For one, Breadon became head of Boston’s Committee on Redistricting after Council President Ed Flynn temporarily suspended Hyde Park Councilor Ricardo Arroyo from his chairmanship after the Boston Globe’s reporting revealed Arroyo’s being the subject of a pair of nearly 20-year-old sexual assault investigations.

As Redistricting Vice Chair, Breadon became the new Chair by default.

At the council’s tense last meeting, several councilors of color decried Arroyo’s suspension as an unfair and politically motivated move meant to ensure that a white councilor would again oversee the process of reshaping boundaries to govern voting and political representation for the next decade.

Breadon said Monday her goal is to have a “fair, open and transparent process” that redraws districts according to the city’s latest demographics.

“For me, personally, I’m the district councilor for Allston-Brighton, District 9. Our boundaries will not change,” she said with a chuckle. “I’m confident that I don’t have any particular agenda, I just want to do a good job and have a fair and equitable process that produces a good redistricting map for this round.”

Another factor complicating this year’s redistricting process is that the City of Boston added 20 precincts, the small units that make up council districts, prior to adjusting its district lines, making it difficult for officials to see where logical boundaries might now fall.

The BPDA has issued at least three separate publications to help inform redistricting, but none of the resources illustrate the new lines.

“We’d like the demographic data to correspond with those new precincts,” Breadon said.

Neither the mayor’s office nor the BPDA immediately responded Monday to GBH News' request for comment on the subpoena order.

Census data shows Boston grew nearly 10% from 2010 to 2020 with its Asian/Pacific Islander population growing by 38% and its Hispanic population growing by 17%. The city’s white population grew by 3.8%.

At the same time, Boston’s Black/African-American population citywide fell by 6.4%. The city’s American Indian and Alaska Native population also fell by nearly 20%.

Breadon represents a neighborhood with one of the biggest population losses, according to BPDA data. Allston, which is known as a hotspot for college students, saw a total population drop of 5.9% between the 2010 and 2020 census.

City Hall insiders have indicated the mayor is gearing up to issue a formal challenge to the city’s census count since it was lower than recent estimates projected, particularly among areas where college students typically reside.

The results of an undercount challenge, Breadon said, would not interfere with Boston’s redistricting.

“We’re on a very tight timeline. We have to have this process finished and ready for final approval by the first week of November,” she said.

The council district maps must be approved by the council and the mayor before the next regular municipal election so that those seeking to run for a District City Council seat can demonstrate residency for the prior year.

State law is unclear about what happens if the council fails to approve maps the mayor deems acceptable. A 1982 law set up an emergency provision allowing the mayor to propose a plan to a local election review commission, but that law only appears to apply to that specific year.