A U.S. Border Patrol agent takes down personal data from Salvadorian mother Ana Esmeralda and her son Manuel Alexander, 2, after they were taken into custody on July 02, 2019 in Los Ebanos, Texas.

In early 2019, with the crisis at the U.S.'s southern border reaching a tipping point, immigration surged to become the issue that small business owners said they cared about the most. In the first quarter of this year, more than a quarter of small business owners (27%) named immigration as the top issue, when only a year prior just 11% had said the same.

But those concerns among small business owners do not extend to their work. The percentage of small business owners who expect any effect on their businesses — positive or negative — as a result of changes to immigration policy has barely budged in the past two years. Even when concerns about immigration spiked, about 6 in 10 small business owners said they didn't expect immigration policy to impact their businesses, the same as in previous quarters.

While the crisis at the border continues, the concerns among small business owners already seem to be fading. This quarter the percent naming immigration the top issue is down five percentage points from its peak six months ago.

These data come from the quarterly CNBC/SurveyMonkey Small Business Survey, a regular check-in on the state of small business optimism in the United States. The latest survey was fielded July 29 to Aug. 4 among a sample of nearly 2,300 small business owners.

Majorities of small business owners say that immigration policy has had no impact on their business in the past 12 months (69%) and that they expect immigration policy to have no effect on their business in the next 12 months (61%).

However, among the minority who have been affected by immigration policy thus far, three times as many small business owners say they have been hurt by the U.S.'s immigration policy as the number who say they've been helped (21% vs. 7%). For this small subset, hiring difficulties have only become more problematic thanks to the immigration crisis.

Nearly half of small business owners (46%) who say immigration policy has hurt their business in the last 12 months say they've hired or attempted to hire new employees in the same time period. Of these small business owners, 52% say U.S. immigration policy has made it more difficult to hire new workers.