75% of the Texas vote is in the 26 largest counties, so a small change in the rural vote helps in only a small way. Cruz really has no upside among rural voters, so any change will be to Beto's benefit.
 
	Here is a list of those counties showing the number of Republican votes in 2016 and 2012, the Republican percentage of the total vote in 2016 and 2012, and the percentage lost by the Republicans (except for Jefferson Co.) (and gained by the non-republican candidates). I also make some rough predictions for 2018. 
 
	GUADALUPE    36,632    33,117    63.4    66.9    -3.5 
	COMAL        45,136    39,318    72.6    76.3    -3.7 
	ELLIS        44,941    39,574    70.6    73.1    -2.5 
	BRAZOS        38,738    37,209    57.6    66.5    -8.9 
	HAYS        33,826    31,661    46.9    53.7    -6.8 
	MCLENNAN    48,260    47,903    61.0    64.3    -3.2 
	SMITH        58,930    57,331    69.5    72.0    -2.5 
	JEFFERSON    42,862    43,242    48.9    48.8    0.1 
	CAMERON        29,472    26,099    32.0    33.9    -1.9 
	BELL        51,998    49,574    54.7    57.5    -2.8 
	LUBBOCK        65,651    63,469    66.3    69.6    -3.3 
	NUECES        50,766    48,966    48.6    51.0    -2.3 
	BRAZORIA    72,791    70,862    60.1    66.4    -6.3 
	GALVESTON    73,757    69,059    60.0    62.7    -2.7 
	HIDALGO        48,642    39,865    28.0    28.6    -0.6 
	WILLIAMSON    104,175    97,006    51.3    59.4    -8.1 
	MONTGOMERY    150,314    137,969    73.5    79.7    -6.2 
	EL PASO        55,512    57,150    25.9    33.1    -7.2 
	FORT BEND    117,291    116,126    44.8    52.9    -8.2 
	DENTON        170,603    157,579    57.1    64.9    -7.8 
	COLLIN        201,014    196,888    55.6    65.0    -9.4 
	TRAVIS        127,209    140,152    27.1    36.2    -9.1 
	BEXAR        240,333    241,617    40.8    47.0    -6.3 
	TARRANT        345,921    348,920    51.7    57.1    -5.4 
	DALLAS        262,945    295,813    34.6    41.7    -7.0 
	HARRIS        545,955    586,073    41.6    49.3    -7.7
 
	2018 Senate Race 
	Beto (>60%) - Harris, Dallas, Bexar, Travis, El Paso, Hidalgo, Cameron  
	Beto (53-60%) - Fort Bend, Nueces, Jefferson, Hays  
	Beto (50-53% - Tarrant, Williamson (Flipped to Democrats) 
	Cruz (50-53%) - Collin, Denton, Bell (Will Flip in 2020) 
	Cruz (53-60%) - Galveston, Brazoria, Mclennan, Brazos, Guadalupe 
	Cruz (>60%) - Montgomery, Lubbock, Smith, Ellis, Comal