Colorado’s middle-aged citizens, the 41-60 cohort, decreased by almost 46,500 active voters from 2012 to 2016. Republicans lost 26,166 in that group and Democrats lost 20,280.

Where did they go? Many moved to the 61-70 cohort. Democrats gained 31,000 active older voters, roughly 10,000 more than they lost in the 41-60 crowd. Republicans grew by 24,000 voters, about 2,000 down from their middle age losses.

At the same time, Democrats increased by almost 19,000 active voters in the 26-40 range while Republicans added fewer than 3000.

Big gains in total voter numbers occurred in metro Denver, with probable impacts on districts with tight races. The race between Republican U.S. Rep. Mike Coffman and his Democratic challenger, state Sen. Morgan Carroll, in the 6th Congressional District will be particularly telling with its large number of new voters.

The 6th CD runs from Brighton in Adams County through Aurora and Centennial in Arapahoe County, on south to Highlands Ranch in Douglas County. Arapahoe County makes up about 66 percent of the district. Arapahoe County put on 89,000 new active voters since 2012. Adams County put on 63,000, and Douglas County put on 42,000.

The gender split in Arapahoe County is markedly uneven, with 54,000 new active women voters in Arapahoe and only 35,000 men among that group. Adams and Douglas counties split roughly even, with something over 30,000 for both men and women in Adams, and 21,000 new men and 21,000 new women voters in Douglas. Adams has about 11,000 more active women voters than men. Douglas went from an even number of men and women active voters in 2012 to a surplus of 6,000 among women in 2016.

Coffman won re-election in his redrawn district in 2012 and 2014 – the latter a non-presidential election year – against male opponents. Now he faces Carroll in a presidential year with 19,000 more new women voters in his district than men, according to data from the secretary of state. Both campaigns have made big ad buys. Coffman has proclaimed his general distaste for Republican presidential nominee Donald Trump, and he’s been learning Spanish. Is that enough?

Both candidates will definitely run ads with positive messages appealing to women. Carroll appears to be receiving more financial support as Trump’s candidacy becomes an albatross for Coffman. No better time will come for Democrats to win the 6th, at least until the next redistricting before the 2022 election.

The race for state Senate District 26 between Democratic state Rep. Daniel Kagan and Arapahoe County Commissioner Nancy Doty, a Republican, is equally compelling. State Sen. Linda Newell, a Democrat, won the seat twice and is term-limited. Her race was tight the first time, easier the second time. The district had a slight Republican advantage in 2012, but now Democrats are ahead by 2,500 voters.

Kagan has won some squeakers, so he knows how to operate with close calls, especially with fundraising. Doty is a well-liked former county clerk as well as current county commissioner with a long history as an active Republican in former Gov. Bill Owens’ administration. Both candidates have raised over $100,000, but Kagan is ahead by about $30,000.

If Coffman and Doty lose, that will signify that most of Arapahoe County has switched from a Republican bastion to Democratic territory, at least in presidential years.

The gender element of the presidential contest makes these close races unpredictable. But if single male voters want to meet single female voters, their best bet is in Arapahoe County.