As the redistricting process rumbles forward nationwide, one key question emerges every time a new map is adopted: How much of the population in each new district comes from each old district? Scrutinizing a map won’t tell you, but fortunately, Daily Kos Elections’ redistribution tables will. We’ve put together tables for all of the states that have completed congressional redistricting so far and will keep updating this resource until every state is finished.

So how do you use these tables? Just below is an example from Oregon, which was the first state to pass a new congressional map in 2021. We’ll walk you through how to read it:

The first thing to note is that the top and bottom halves both contain the same information, except that the first is expressed in raw population numbers and the second in percentages. We’ll use the percentages in this example.

Along the left-hand side, you’ll see a column containing district numbers for the new districts, while across the top, you’ll see a row listing numbers for the old districts. We’ll scan down the left-hand column to pick an interesting district, in this case, the brand-new 6th District, which Oregon earned in reapportionment thanks to its comparatively high population growth.

From there, we’ll scan horizontally until we see cells that have percentages in them—and boom, we hit one right away in the very first box with “40.48%.” If you then scan upward, you’ll see that this cell corresponds to the old 1st District, represented in the current Congress by Democrat Suzanne Bonamici. What this means is that 40.48% of the population of the new 6th is drawn from the old 1st. Keep scanning further and the next box you’ll hit shows that 59.52% of the old 5th District makes up the remainder of the new 6th. Together, as the final column shows, these add up to 100%.

(To translate these percentages into actual population figures, simply find the corresponding cell in the top chart. For the 6th, we see that about 286,000 people come from the old 1st and 420,000 hail from the old 5th, for a shade over 706,000 in total—the same population, give or take a handful, as every other district.)

This aspect of the new map presented a conundrum for Democratic Rep. Kurt Schrader, who currently represents the old 5th: Most of his constituents, who’ve seen his name on the ballot for Congress in every election since 2008, now live in the 6th. However, his hometown of Canby—his geographic base—is still in the new 5th.

Schrader in fact considered both districts when evaluating his re-election plans, but he ultimately decided to run in the new 5th, even though a smaller share of its population comes from the old 5th compared to the proportion that makes up the 6th. You can see just how much in the next-to-last column of the next-to-last line: 46.78%.

That line also illustrates just how much upheaval Schrader’s turf underwent. In fact, the new 5th takes in a portion of every previous district, something you can see illustrated in the map at the top of this post. All of the other districts, however, largely remained the same.

In each row, the cell with the largest percentage is highlighted in bold text, showing which old district each new district drew most heavily from. For the new 1st, that was the old 1st (82%); for the new 2nd, the old 2nd (92%), and so forth. In each case, except for the 5th, the vast majority of constituents stayed put. You could even argue that the 5th is actually the state’s “new” district since it bears the least in common with its predecessor, sharing less DNA with the old 5th than the 6th does!

What if you’d like to know the inverse of all this: How much of each old district wound up in each new district? We’ve got that information, too. Scroll past the green horizontal divider until you reach the second pair of tables:

You read these the same way. Here we see that the old 5th got broken up five ways, with population going to every new district except the 2nd. (There’s even a small eastern nubbin that did in fact wind up in the 2nd District, but no one lives there so it’s not reflected in the table above, though you can see it on our map.) Unsurprisingly, given what we learned above, the largest chunk of the old 5th has wound up in the 6th—49.6%, which accordingly is boldfaced.

One difference you’ll note, though, is in the final column of the top table. Because each district has experienced different rates of growth over the past decade, the population figures (which are taken from the 2020 census) show different totals. They range from about 824,000 in the 4th to 864,000 in the 1st. In every state, these variances have to be brought as close to zero as possible in order to ensure compliance with the constitutional doctrine of “one person, one vote.”

Because Oregon gained a seat, every district had to shed population, but in states whose congressional delegation is holding steady, that last column will show you which districts need to add people and which need to slim down. For instance, here’s Alabama, whose award of seven seats in Congress last decade remains unchanged for the coming one:

With a 2020 census population of just over 5 million, Alabama’s districts needed to achieve a population of about 718,000 each. That meant the 1st, 3rd, 5th, and 6th all had to shrink so that the 2nd, 4th, and 7th could grow.

As each state enacts a new congressional map, we’re adding tables like those above to our redistribution database, with each state on a separate tab. It’s a resource very much worth bookmarking. Should any maps change due to litigation or mid-decade redistricting, we’ll update accordingly. You can also find our database for the previous decade right here.