The data shows that 85 percent of students who entered high school in 2007 graduated four years later.
That number rose to 89 percent for Robert E. Lee High School and 81 percent for John Tyler High School for the 2011 seniors.
These figures represent significant improvement from 2007 when the rate dipped to 64 percent for John Tyler High School and 74 percent for the district as a whole. Lee stood at 82 percent that year.
Dr. Karen Raney, TISD's director of assessment and accountability, said part of the improvement in graduation and dropout rates is a result of better data reporting.
She said her department has improved systems, which in turn have helped campus counselors keep better track of when a student starts high school and where they are on the road to completion.
"We want to be sure that we're focused on getting the kids in that cohort across the stage," she said.
The fact that neither high school's graduation rate reaches 100 percent does not mean the remaining 11 to 19 percent of students in that class dropped out.
It just means those students started as freshman and didn't finish at the same school. Some of them could have dropped out. They also could have moved to another school or could still be in school in TISD.
The dropout rates for Lee and John Tyler were 1 percent for each campus during the 2010-11 school year.
That was down from 2 percent in 2006-07 for Lee and 4 percent in 2006-07 for John Tyler.
The district has several measures aimed at keeping students in school and on track to graduate.
TISD spokeswoman Dawn Parnell wrote in an email that TISD students are placed in cohorts starting in the ninth grade.
Academic progress is closely monitored in the cohort so that if the student falls behind, the district can provide immediate intervention.
The district continues working to improve instruction and better align it to state testing standards.
For students who do fall behind, the district provides credit recovery opportunities, including the PACE program and online options, Ms. Parnell wrote.
Statewide, the on-time graduation rate reached 78.9 percent for the 2009-10 school year, the most recent data available in a study released this week by the National Center for Education Statistics, which is housed in the U.S. Department of Education.
The on-time graduation rate estimates the percentage of high school students who graduate within four years of starting the ninth grade, according to the report.
Texas' rate was slightly higher than the national average of 78.2 percent and fell in the middle when compared to states across the nation. Some 24 states had higher four-year graduation rates, according to the report.
About 2.7 percent of Texas high school students dropped out during the 2009-10 school year down from an eight-year high of 4.3 percent during the 2005-06 school year. The Texas rate fell below the national average of 3.4 percent.
The findings were not as impressive as a separate, federal education report released in November that put Texas' four-year graduation rate at 86 percent for the Class of 2011, according to the Associated Press.
A Texas Education Agency spokeswoman said the difference in the data is that this week's report estimates high school attrition rates among ninth-graders over four years, while the state tracks actual cases, which allows it to adjust for specific situations such as a student moving away, according to the Associated Press.