This story is part of the KXAN Data Hub, where numbers help tell the whole story.We've created several data-driven stories and databases on topics including weather and climate, politics, education, sports and growth in Texas. Each story in the KXAN Data Hub is updated as new data becomes available. KXAN (AUSTIN) — For the past three decades, Texas has been a Republican stronghold. In fact, no Democrat has won statewide office since 1994. But the margin between Republicans and Democrats in recent years has been narrowing. In the 2014 gubernatorial election, when Greg Abbott became governor, he beat Wendy Davis by more than 20 percentage points. By the 2022 gubernatorial election, Abbott's margin of victory was cut to about 11 percentage points. 234 of Texas’ 254 counties swung toward Trump in 2024 election The margin in presidential elections have been even closer. Mitt Romney carried Texas in 2012 by about 16 percentage points. Donald Trump won the state in 2016 by 9 percentage points, and less than 6 percentage points in 2020. He was able to widen the margin to almost 14 points in the 2024 presidential election. What are the reddest and bluest counties? The base of support for Democrats in the past several cycles has been in large cities, like Austin, Houston, Dallas and El Paso, and communities in South Texas and the Rio Grande Valley, although the latter have been trending rightward. Republicans have enjoyed strong support in more rural areas, like the Panhandle, West Texas and East Texas. A comprehensive map of how Texans voted in the 2022 gubernatorial election To determine the reddest and bluest counties, KXAN calculated the average margin of victory in each county using election results in the 2018 and 2022 gubernatorial elections and the 2020 and 2024 presidential elections. Based on this average, Roberts County, northeast of Amarillo, is the reddest county in the state. Over the past four elections, the margin of victory for Republican candidates there has averaged 93.15 percentage points. Borden and King counties, both near Lubbock, are right behind, each with an average Republican margin of victory of more than 91 points. Twenty other counties have average Republican margins of 80 points or higher, and a further 53 have an average margin of 70 points or higher. Of counties with more than 100,000 registered voters, Parker County, west of Fort Worth, is the strongest county for Republicans. GOP candidates there win on average by 66.68 points. On the opposite end of the spectrum, Travis County, home to Austin, has the highest average margin of victory for Democrats. From 2018 to 2024, Democratic candidates won by an average of 41.87 points. Four other counties have given Democrats an average margin of victory of more than 25 points: Presidio, Zavala, El Paso and Dallas. Beyond those, only 14 counties tend to vote for Democrats on average. Which counties are the closest? Since 2016, five counties have been decided by less than 5 points on average. The closest has been Culberson County, east of El Paso, which has given Republicans an average margin of victory of 2.46 points. Next closest is the suburban Williamson County, north of Austin, which has given Republicans an average margin of 3.07 points, then Zapata County, on the border south of Laredo, which has an average Republican margin of 3.66 points. Landslides to nail-biters: A history of presidential elections in Texas Fort Bend and Tarrant counties both have average margins of less than 5 points — Fort Bend in favor of Democrats and Tarrant in favor of Republicans. Which counties have seen the biggest shifts? KXAN looked at results in the 2016, 2020 and 2024 presidential elections and 2018 and 2022 gubernatorial elections to determine the average shift in each county between each election cycle. Since 2016, several counties, especially in South Texas, have sprinted to the right, while suburban counties have moved leftward. The most dramatic changes have happened in Starr, Maverick, Zapata, Kenedy and Webb counties. In each election, Starr County moved an average of 19.04 points to the right, while the others all shifted rightward by an average of more than 13 points each cycle. In total, 216 of the state's 254 counties have seen average movement toward the Republicans each cycle since 2016, while 38 counties have shifted toward the Democrats. Most notable for Democrats is suburban Kaufman County, east of Dallas, which has seen an average leftward shift of 4.73 points each election cycle. Neighboring Ellis County has moved to the left by an average of 3.5 points each cycle. On a statewide level, Texas has seen an average shift to the Republicans of 1.17 points each election cycle since 2016.