DOVER — Delaware lawmakers announced Thursday they will return in the fall for a special session to redraw the borders of the state’s 62 legislative jurisdictions.

Redistricting takes place every 10 years, meaning it is set to go into effect for the 2022 election. The change is based on population trends from the decennial federal census, but information from the census may not be available until the summer, several months later than usual.

According to the National Conference of State Legislatures, redistricting data from the U.S. Census Bureau likely won’t be given to the states until at least August.

With the General Assembly wrapping up its regularly scheduled business every year by July 1, that timetable creates a problem.

“Redistricting is an extremely complex process, but we have always met our obligation,” House Speaker Pete Schwartzkopf, a Rehoboth Beach Democrat, said in a statement. “However, our redistricting schedule — which would have started this spring — has been thrown off because of problems due to the previous presidential administration and the ongoing pandemic. Rather than leave things in doubt, we feel it is best to be upfront and announce this fall session now so everyone can plan accordingly.”

Although the specific details are still being decided, lawmakers will likely return in the fall over the course of several weeks, according to Rep. Schwartzkopf and Senate President Pro Tempore Dave Sokola, a Newark Democrat.

Lawmakers will be tasked with redrawing boundaries for 21 Senate districts and 41 House districts, while keeping populations close to even, making districts contiguous and compact and adding or maintaining majority-minority areas where possible. Some states use independent commissions, but Delaware leaves redistricting up to legislators.

Districts are adjusted based on census blocks, not streets or municipalities. Individual census blocks vary in size and population, with ones in Wilmington being more compact and crowded than ones in rural Sussex County, for instance.

Incarcerated Delawareans count based on their last known addresses, while residents of other states imprisoned here will not be considered. This avoids skewing the districts containing state prisons by counting inmates, who may not be able to vote.

The concept of “one person, one vote” remains a core principle in drawing boundaries.

In 2012, Rep. Schwartzkopf, then the majority leader, coordinated the effort for House Democrats, working with aides and getting input from other legislators. House Republicans provided their own map, and the two sides worked to find as much common ground as possible, although Democrats, as the majority, ultimately had substantially more say.

A similar process took place in the Senate.

That year, House districts were required to have 21,900 residents each, give or take 5%, with natural boundaries like roads or streams, while Senate ones averaged 42,800. A public hearing was held, and Delawareans were allowed to weigh in on the potential changes online, as well.

Reflecting population trends, legislators eliminated three districts, all in northern New Castle County. In their place, the General Assembly added one House district in southern New Castle that crosses over into Kent County, as well as House and Senate districts covering eastern Sussex County.

Many of the details of the upcoming process, such as who will lead it, will be determined in the coming weeks and months.

“Just like every one of our constituents, we have had to make adjustments to account for the failed leadership of the previous administration and this is no different,” Sen. Sokola said in a statement. “On the bright side, however, Speaker Schwartzkopf and I hope these extra session days will allow our members to focus all of their attention on this important process and provide greater opportunity for public input than ever before.”