Typically, the state constitution provides a set of rules, but these are interpreted in light of the US Supreme Courts reapportionment decisions based on the equal protection clause of the 14th Amendment. The districts must also comply with the Voting Rights Act, which outlaws/requires racial gerrymandering. They are often litigated in the same manner as congressional districts.
Texas Senate:
"The State shall be divided into Senatorial Districts of contiguous territory, and each district shall be entitled to elect one Senator."
This was revised in 2001 in a general cleanup of the constitution. Formerly, the Senate districts were supposed to be based on the number of qualified electors (rather than population), but since no one knew how to determine the number of qualified electors, they were based on population. In addition, the old constitution said that no county could have more than one senator, but that was ignored because some counties had too much population (Harris County has a population equivalent to about 5 senate districts, for example).
Though the Texas constitution now says nothing about population equality, this is implicit under the US Constitution. Generally, the US Supreme Court has permitted a range of 10% between the smallest and largest district (not necessarily 95% to 105%, 93% to 103% works as well).
Texas House:
"The members of the House of Representatives shall be apportioned among the several counties, according to the number of population in each, as nearly as may be, on a ratio obtained by dividing the population of the State, as ascertained by the most recent United States census, by the number of members of which the House is composed; provided, that whenever a single county has sufficient population to be entitled to a Representative, such county shall be formed into a separate Representative District, and when two or more counties are required to make up the ratio of representation, such counties shall be contiguous to each other; and when any one county has more than sufficient population to be entitled to one or more Representatives, such Representative or Representatives shall be apportioned to such county, and for any surplus of population it may be joined in a Representative District with any other contiguous county or counties."
There are 3 cases:
a) Large counties entitled to a whole number of representatives.
b) Large counties entitled to a whole number and a fraction number of representatives.
c) Small counties entitled to less than one representative.
There are about 8 and 15 counties that fall in the first two categories,, respectively, and 231 counties in the second category (less than about 140,000 in population).
The distinction between (a) and (b) is based on whether the average population that would be necessary for districts in a county would be within the 95% to 105% range.
For example, a county with a population equivalent to 5.20 representatives would be apportioned 5 representatives, who would each represent a district with around 104% of the statewide average. Note that the 10% range is statewide. In a county like this, the population range between districts would be fairly close because the top limit of 105% means that the smallest could only be around 103%.
On the other hand, a county with a population equivalent to 5.40 representatives could not have 5 districts with 108% of the population, but instead would be divided into 5 districts, with the excess of 0.40 combined with adjacent counties or parts of counties.
After you have split the counties into the 3 classes, the surplus from those in class (b) and all the small counties are combined in districts. Counties may not be split (with the surplus from the larger counties treated as counties). In 2001, 99 districts were wholly contained within counties, and 51 combined counties. Because of the limitation on splitting counties, the combination of counties is often mandatory (if you have a county entitled to 0.60 representatives, you will need to find an adjacent county or counties that have a population equivalent to 0.35 and 0.45 representatives.
The Texas Constitution doesn't say anything about districts within counties, and before the USSC reapportionment rulings, all representatives would be elected county-wide. In addition, when there was a surplus, the "surplus" representative would be elected from the whole territory. Example, if you had one county entitled to 1.5 representatives, and a neighbor entitled to 0.5 representatives, the larger county would elect 1 representative countywide, and the two counties together would elect the second representative (with 75% of the vote coming from the larger county). But since the 1960s representatives have been elected from single member districts.
Usually, it is impossible to avoid all county splits and remain within the 95-105% range. In that case, the US Constitution overrides the Texas Constitution and additional splits are made. Essentially an attempt is made to follow the Texas Constitution as much as possible as is consistent with the US Constitution, rather than simply disregarding the Texas Constitution.
In Texas, the legislative districts are drawn by the legislature. Traditionally, each house draws its own districts. Two separate bills are then passed to the other house (any legislation must pass both houses, and be signed by the governor). The two houses then meet at the same time to approve the other house's reapportionment plan. Clerks are stationed in the doorway of the two chambers so that they can signal down the corridor to the other chamber. The two bills are then gaveled at the same time so that there can't be a double cross.
In 2001, the legislature did not approve new legislative districts. But unlike the case with the congressional district boundaries, the Texas Constitution provides for a Legislative Redistricting Board of 5 members (the Lt.Governor (as presiding officer of the Senate), the Speaker of the House, the Comptroller, the Attorney General, and the Land Commissioner.
They drew the boundaries that can be seen at
Texas Legislative Council Redistricting - Click on RedviewerAfter the LRB or the legislature draws district boundaries, they are then reviewed by the US Department of Justice to verify that they comply with the Voting Rights Act. The DoJ required a few small adjustments, which were incorporated in the LRB plan. The LRB plan was also reviewed by same federal district court that drew the congressional district boundaries.
During the 1990s the legislative districts were (re)drawn 5 times, but so far, they have only been drawn once.
In Texas, there are 31 Senators, who are elected for 4 year terms. After the election following redistricting, senators are split into groups of 16 and 15 by lot. 1/2 serve an initial term of 2 years, with the subsequent term for their district of 4 years, and the other half serving an initial 4-year term.
So 1/2 the Senators will be elected in 2002, 2006, and 2010; and the other half will be elected in 2002, 2004, and 2008. A new reapportionment will occur following the 2010 US Census, and all senators will run from the new districts.
The 150 Representatives are elected for 2 year terms.
Because 150:31 is not an integer ratio, there is no particular relationship between House and Senate districts. A typical Senate district might contain parts of between 6 and 12 House district.
There are fewer State Senators than US Representatives (31 v. 32), so Senate districts are slightly larger by 3% than the Congressional Districts.
