The Twin Cities metro has become a hotbed for new millennials, but finding an affordable rental hasn't gotting any easier. During the past seven years the millennial population in Hennepin County alone has increased nearly 25 percent, making it one of the top 25 for the biggest increase in millennials nationwide, according to RealtyTrac. During that same period the average fair market rent for a three-bedroom apartment rose to $1,403, far above the national average.

RealtyTrac said the top markets with the biggest increase in the percentage of millennials over the past seven years were counties in Washington D.C., San Francisco and Denver, all of which saw an increase of more than 50 percent in the share of the population that is millennials.

Other highlights from the report:

  • The average 2015 fair market rent in the 25 counties with the biggest increase in millennials is expected to hit $1,459, 19 percent above the national average for all counties analyzed.
  • On average rents increased 3 percent from a year ago in these counties, with the standouts being Denver County and Midland County, Texas, both of which saw fair market rents increase more than 20 percent.
  • Median home prices increased 9 percent from a year ago in these counties on average compared to an average 6 percent increase among all counties analyzed nationwide.
  • The average unemployment rate among these counties was 5.2 percent in October compared to an average of 5.5 percent for all counties analyzed.