From VoteSaveAmerica:
https://secure.actblue.com/donate/donate-save-americaOur smart friends at the data firm Civis crunched the numbers and found that donating to these 20 specific House candidates would give you the most bang for your buck. Here’s why:
1. They are expected to be extremely close races
2. They have less expensive media markets so each advertising dollar will go a lot further
3. You donations will actually help improve Democrats' chances of winning in these races by boosting voter turnout
In fact, according to the Head of Political Data Science at Civis, every dollar you donate toward this list of races would generate roughly 2.2 times as many votes than if you just donated to the 20 closest races across the country. The list includes Alyse Galvin (Alaska) and Kathleen Williams (Montana, running against the unspeakable Gianforte).