This state-level poll round-up is from August 20-Sept 2, and I have only included the 13 states for which there has been polling which either Romney or Obama won with less than 10% margin in 2012 (except SC, which Romney won with 10.5%, and NM, which Obama won with 10.1%), ie, "battleground" states. The table shows each of the 13 states, their electoral votes, the 2012 Romney-Obama win margins, the early August (2016) polling results, and in the final column, polls since August 20th. In all cases except for Florida and North Carolina, the trend seems to be a shift in Trump's favor. Not nearly enough to win him the election at this point, but all of the states where Clinton was ahead in early August, now show a smaller lead, and the states where Trump was ahead, now show larger leads. In fact, Iowa, while still within the margin of error, has shifted to the Trump camp.
In each of these cases, all of the polls for these 13 states are still showing within the margin of error, except for a few oddities. For example, on August 23rd, two universities generated polls showing incredibly strong leads for Clinton: Saint Leo gave her a 14% lead in Florida, and Roanoke a 19% lead in Virginia. Later polls by other sources gave both states to Clinton with a 1-2% margin. Thus, the size of the Clinton leads shown in this table for those two states should be viewed suspiciously. The outcomes are consistent with each other, and with the previous polling in these states, but not the size of the leads--ie, they all still show Clinton winning these states.
In a similar trend, the polling margin wins are getting closer to the Obama-Romney win margins in 2012. For example, in early August, polls gave Wisconsin to Clinton by 15%, and now by 5%, far closer to the 7% win by Obama in 2012. On the other hand, Trump's polling in these battleground states are still far from Romney's win margins. In each case, even though his lead seems to have grown since early August, he is winning these states by less than 4%, whereas Romney won South Carolina, Missouri, and Arizona by almost 10%.
If there is any trend in this data, it's in Trump's favor. However, all of this was before his Mexico visit + Arizona speech debacle, and his various surrogate crises from just the last few days: a disgraced, lying pastor, the promise of a "taco truck on every corner if Trump doesn't win", and increasingly public abandonment of Trump by the Republican Party leadership, including senators trying to hold onto their jobs. While state-level races seem to mirror the national polling, a tightening of the race, there is still no evidence that Trump can win states that Romney lost in 2012. The problem for Trump has been the same since I started these analyses in July--the presidential race isn't national, it's state-by-state, and most states' electoral votes are already locked into a party by demographics and history. The battleground states that Trump must switch from purple to red, simply are not polling in his favor, and none of his rhetoric, surrogates, or campaign behavior seem to be doing anything but pushing these states away from him.