OMAHA — The Florida Gators were awarded the top seed in the N.C.A.A. baseball tournament Monday, leading a record four Southeastern Conference teams among the eight national seeds. Florida (47-13) was ranked No. 1 in the polls for most of the season and finished as the runner-up to Texas A&M in the SEC tournament. It has never won a national championship in baseball.

The Gators have been a national seed seven times under Coach Kevin O'Sullivan, including No. 1 in 2012. No top seed has won the championship since Miami in 1999, the first year of the current tournament structure.

The other SEC national seeds are No. 4 Texas A&M (45-14), No. 6 Mississippi State (41-16-1) and No. 8 Louisiana State (42-18).

The Atlantic Coast Conference has three national seeds in No. 2 Louisville (47-12), No. 3 Miami (45-11) and No. 7 Clemson (42-18). The Big 12 has the other national seed in No. 5 Texas Tech (41-16).

The SEC also set a record Sunday when the N.C.A.A. selection committee picked seven of its teams to host regionals. Six A.C.C. teams will host regionals, including the defending national champion, Virginia (37-20).

The 16 regionals are scheduled from Friday through next Monday, and each includes four teams playing a double-elimination format. Regional winners advance the next week to best-of-three super regionals, which will determine the eight teams that will play in the College World Series in Omaha beginning June 18.

The 64-team field is made up of 31 automatic qualifiers and 33 at-large selections.

Ten A.C.C. teams are in the tournament, tying the record for the most from one conference.

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"I've never seen a league as strong as this year," Florida State Coach Mike Martin, who has led the Seminoles for 37 years, said. "Ten teams is quite an accomplishment."

North Carolina nearly gave the A.C.C. an 11th entry. At No. 19, the Tar Heels (34-21) have the highest Rating Percentage Index of any team ever left out. The R.P.I. is one of several metrics the selection committee uses to determine at-large teams.

Joel Erdmann, the selection committee's chairman, said the Tar Heels were the first team left out after following an 18-2 start with a 16-19 finish and a fifth-place ranking, at 13-17, in the A.C.C.'s Coastal Division.

"What makes it unique is they are within the top conference in the nation, but when you really break down their field of work, their résumé, they, within the conference, struggled a bit," Erdmann said.

Four teams are in for the first time as automatic qualifiers: Fairfield (32-24) of the Metro Atlantic Athletic Conference, Alabama State (38-15) of the Southwestern Athletic Conference, Utah Valley (37-21) of the Western Athletic Conference, and St. Mary's College of California (33-23) of the West Coast Conference.

Western Michigan (22-32) upset Kent State in the Mid-American Conference title game and was one of two teams that made it as automatic qualifiers with losing records.

The other was Utah (25-27), which won the Pacific-12 Conference regular-season title — the league does not hold a conference tournament — with a 19-11 league mark. The Utes are in their fifth season in the Pac-12 and finished last in each of the previous four, never winning more than seven conference games.

Erdmann said the final three teams picked for at-large bids were Southeastern Louisiana (39-19, No. 40 R.P.I.), Nebraska (37-20, No. 48) and South Alabama (40-20, No. 50). The next two teams left out after North Carolina were Oregon State (35-19, No. 44) and West Virginia (36-22, No. 61).