It appears that New York and New Jersey (and neighboring areas) are the main Jewish concentrations by population.... (making it much easier to mantain a kosher lifestyle in those places)

Estimated Total Jewish Percent
Jewish Population Population* of Total
Alabama 0.2%
Alaska 0.5%
Arizona 1.8%
Arkansas 0.1%
California 3.3%
Colorado 1.7%
Connecticut 3.2%
Delaware 1.6%
District of Columbia 5.1%
Florida 3.7%
Georgia 1.4%
Hawaii 0.5%
Idaho 0.1%
Illinois 2.2%
Indiana 0.3%
Iowa 0.2%
Kansas 0.7%
Kentucky 0.3%
Louisiana 0.4%
Maine 0.8%
Maryland 4.2%
Massachusetts 4.3%
Michigan 0.9%
Minnesota 0.9%
Mississippi 0.1%
Missouri 1.0%
Montana 0.1%
Nebraska 0.4%
Nevada 2.9%
New Hampshire 0.8%
New Jersey 5.5%
New Mexico 0.6%
New York 8.4%
North Carolina 0.3%
North Dakota 0.1%
Ohio 1.3%
Oklahoma 0.1%
Oregon 0.9%
Pennsylvania 2.3%
Rhode Island 1.7%
South Carolina 0.3%
South Dakota (z)%
Tennessee 0.3%
Texas 0.6%
Utah 0.2%
Vermont 0.9%
Virginia 1.3%
Washington 0.7%
West Virginia 0.1%
Wisconsin 0.5%
Wyoming 0.1%