This year is shaping up to be a better year for U.S. bank and thrift mergers and acquisitions than 2012, at least by some measures. Through Nov. 22, 117 deals with announced value over $1 million were announced in 2013, for a total value of $13.3 billion, versus 129 deals worth $11.9 billion in the comparable period in 2012. That's 9% fewer deals, but 12% higher aggregate value.

I doubt that bank M&A advisors are popping champagne corks over the latter fact. They've been waiting for a far bigger turn in activity for a long time.

Aggregate deal count and value in 2007 were 235 and $71 billion, respectively. We are about to end the fifth consecutive year of extremely lean deal activity, leaner than in the early 1990s. The biggest U.S. banks are now immense, and regulatory constraints prevent the bank acquisitions they'd most like to make. And while the economy is showing signs of life, the reversal of the Federal Reserve's quantitative easing program and other macroeconomic issues could very well quash a resurgence of bank M&A activity.

If or when M&A activity does pick up, will it pick up everywhere? No. Several small states have way too many banks. It's been that way for a long time and it's likely to stay that way, because most banks are too small for buyers to bother with.

Rank the 50 states in declining population order, and then layer on the number of banking institutions operating in each state. If you start at the bottom of the list, you discover that no state has even 100 banking institutions operating in it (with "operating" defined as having at least one branch and deposits greater than zero), until you hit Nebraska: the 38th most populous state, with 1.9 million people, and 205 banking institutions. California is the most populous state, with 38 million people, and has 231 institutions. Twenty times as many people, only 13% more banks. Keep progressing up this list, and you'll find that No. 33, Kansas, has 304 institutions, and No. 30, Iowa, has 300. Minnesota has 366. Missouri has 313.

Most of the institutions in these states are tiny, and market share is highly concentrated among each state's five largest institutions, sometimes fewer than five. (This is true for big states too.) Seventy-two Nebraska-based targets have been sold since 1991, or only about three per year. In 57 of them, the buyer was headquartered in Nebraska too; most bank M&A is local. Only four of these deals had an announced value over $100 million. Of the five largest institutions operating in the state, three are Nebraska-based and private, and the other two, Wells Fargo (WFC) and U.S. Bancorp (USB) are very large. There's only one large publicly-traded institution based in the state, First National of Nebraska (FINN), with a $1.6 billion market capitalization; the second largest Nebraska-based institution's market cap is $54 million.

So which bank will mop up all the little Nebraska banks? My guess is no bank will, at least any time soon. And I suspect that the same will prove true for Kansas and Minnesota. Tiny deals aren't meaningfully accretive to buyer EPS, even if they're modestly priced.

So if you think the number of banks in the U.S. should be lower by half or more (I do), I'd encourage patience.

Have greedy sellers waited too long to sell? Probably in several states, but not in all of them. There are 546 institutions in Texas, the second most populous U.S. state (26 million people) and 542 in fifth-ranked Illinois (13 million people). Despite the national slump in bank M&A activity, activity in Texas has remained robust over the last several years, with 59 deals worth $4.3 billion announced since the beginning of 2009. Illinois' activity has been more modest, with 24 deals worth $982 million since the beginning of 2009. Both states appear to have an ample supply of potential consolidators. Still, it's doubtful that the smallest institutions in these two states have much appeal for the likely acquirers; 60% of the institutions in Texas have less than $250 million in deposits.

Are there any states that look especially ripe for activity? Ohio. It is the seventh most populous state (12 million people), and of the ten largest institutions operating in the state, six are based there. 62 publicly-traded institutions are headquartered in the state. Lots of potential acquirers and targets.

With that said, consolidation among the largest banks headquartered in Ohio will eventually lead to dwindling interest in the state's smaller ones, just as it has elsewhere. Targets that recognize this and start choosing partners now have a chance to sell to institutions that themselves get sold. Such "double dips" have become a rarity in recent years.

And the targets that don't recognize this? They'll feel like they're working in Nebraska.

Harvard Winters, a former investment banker, writes research on banks.