U.S. Ban­corp is buy­ing the Chi­ca­go branch net­work of RBS Citizens Financial Group for about $315 mil­lion, as the Minneapolis-based lend­er doub­les its foot­print in the fierce­ly com­pe­ti­tive mar­ket.

The ac­qui­si­tion, ex­pect­ed to close by midsummer, vaults U.S. Bank into among the top 10 banks in the Chicago-area market.

The pur­chase in­cludes the 94 re­tail branch­es of RBS Citizens’ Charter One Bank fran­chise, as well as its small-busi­ness op­er­ations and cer­tain mid­dle-mar­ket re­la­tion­ships, U.S. Bank said Tues­day. U.S. Bank is get­ting 800 employees, de­pos­its of $5.3 bil­lion and $1.1 bil­lion in loans.

“As you look at our dis­tri­bu­tion in Chi­ca­go, we have not had the depth of dis­tri­bu­tion that we would like in a mar­ket of that size,” said John Elmore, vice chair­man of com­muni­ty bank­ing and branch de­liv­er­y for U.S. Bank. “That’s why this is such an ex­cit­ing op­por­tu­ni­ty for us.”

RBS Citizens said it’s carv­ing off its Chi­ca­go branch op­er­ations as it shifts its fo­cus to lar­ger busi­ness cus­tom­ers.

In a note to cli­ents Tues­day, David George, an an­a­lyst at Robert W. Baird & Co. Inc., called the pur­chase “small but stra­tegic.” The pur­chase price was less than what had been expect­ed, he said.

U.S. Bank cur­rent­ly has 90 re­tail branch­es in the Chi­ca­go area and more than 1,800 employees. The lender bought the nam­ing rights to a 40-sto­ry of­fice tower at 190 S. La­Salle St. in down­town Chi­ca­go and plans to have the U.S. Bank sign up on the build­ing some­time this year. It’s keep­ing ex­ist­ing space in the Rook­er­y, a well-known his­tor­ic build­ing down­town.

While U.S. Bank has been in Chi­ca­go for years, its busi­ness there re­al­ly took off af­ter it bought Park National Bank in a 2009 deal with the Federal De­pos­it Insurance Corp.

Mid­dle-mar­ket com­mer­cial cus­tom­ers, or com­panies with rev­e­nue of $20 mil­lion to $500 mil­lion, have produced double-dig­it growth in the past two years, said Mar­sha Cruzan, U.S. Bank’s mar­ket pres­i­dent for Chi­ca­go. U.S. Bank has seen 25 percent growth in small busi­ness lending to com­panies with sales un­der $20 mil­lion.

Elmore said there may be some over­lap be­tween Charter One and U.S. Bank branch­es that are near each oth­er, but U.S. Bank’s goal is to main­tain a broad net­work of branch­es in Chi­ca­go.

“We’re re­al­ly just start­ing the in­te­gra­tion proc­ess now,” Elmore said. “All of those de­tails will be de­ter­mined through­out that proc­ess.”

The Chi­ca­go area has a rep­u­ta­tion as a mar­ket with too many banks that is ripe for con­sol­i­da­tion. The area is domi­nat­ed by JPMorgan Chase & Co. which has near­ly 25 percent mar­ket share by de­pos­its. No. 2 is BMO Har­ris Bank with 12 percent.

RBS Citizens Financial Group is a $120 bil­lion bank based in Providence, R.I. It op­er­ates un­der the Citizens Bank brand in the north­east, and under the Charter One brand in Il­li­nois, Mich­i­gan and O­hi­o.

RBS said it is sell­ing the Chi­ca­go branch­es to fo­cus on core Citizens Bank and Charter One mar­kets where it has bet­ter growth pros­pects. It’s targeting O­hi­o and Mich­i­gan, New Eng­land, the mid-Atlantic, com­mer­cial bank­ing and its na­tion­al plat­forms in­clud­ing fran­chise fi­nance and health care.

In an interview, Robert Matthews, vice chair­man for com­mer­cial bank­ing, emphasized that RBS Citizens is not pulling out of Chicago and is just prioritizing away from business lines that depend heavily on bricks and mortar branches. It will continue offering consumer loans such as residential mortgages and auto loans, and offer a range of commercial loans and services.

“One of the things we’ve been in­vest­ing heav­i­ly in is build­ing a cap­i­tal mar­kets ca­pa­bil­i­ty to help com­panies raise cap­i­tal,” Matthews said. “We’ve seen some very not­able growth.”