See main article: 2004 United States Senate elections.
| Election Name: | 2004 United States Senate election in Maryland |
| Country: | Maryland |
| Type: | presidential |
| Ongoing: | no |
| Previous Election: | 1998 United States Senate election in Maryland |
| Previous Year: | 1998 |
| Next Election: | 2010 United States Senate election in Maryland |
| Next Year: | 2010 |
| Election Date: | November 2, 2004 |
| Image1: | Barbara Mikulski.jpg |
| Nominee1: | Barbara Mikulski |
| Party1: | Democratic Party (United States) |
| Popular Vote1: | 1,504,691 |
| Percentage1: | 64.80% |
| Nominee2: | E. J. Pipkin |
| Party2: | Republican Party (United States) |
| Popular Vote2: | 783,055 |
| Percentage2: | 33.72% |
| Map Size: | 300px |
| U.S. Senator | |
| Before Election: | Barbara Mikulski |
| Before Party: | Democratic Party (United States) |
| After Election: | Barbara Mikulski |
| After Party: | Democratic Party (United States) |
The 2004 United States Senate election in Maryland was held on November 2, 2004. Incumbent Democratic U.S. Senator Barbara Mikulski won re-election to a fourth term. This is the most recent time that a Democratic Senate candidate has won Allegeny County, Caroline County, St. Mary's County or Worcester County. This is the last time that the winning candidate carried a majority of Maryland's county-level jurisdictions in a United States Senate election in Maryland.
| Barbara A. MikulskiDemocratic | E.J. PipkinRepublican | Maria AllwineGreen | Margin | TotalVotes Cast | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| % | % | % | % | ||||||||||
| Allegany | 15238 | 53.67% | 12882 | 45.37% | 271 | 0.95% | 2356 | 8.30% | 28391 | ||||
| Anne Arundel | 129166 | 55.16% | 102522 | 43.79% | 2458 | 1.05% | 26644 | 11.38% | 234146 | ||||
| Baltimore (City) | 172427 | 86.55% | 23759 | 11.93% | 3045 | 1.53% | 148668 | 74.62% | 199231 | ||||
| Baltimore (County) | 217688 | 63.00% | 124092 | 35.91% | 3781 | 1.09% | 93596 | 27.09% | 345561 | ||||
| Calvert | 19543 | 50.97% | 18422 | 48.05% | 374 | 0.98% | 1121 | 2.92% | 38339 | ||||
| Caroline | 5543 | 50.09% | 5439 | 49.15% | 84 | 0.76% | 104 | 0.94% | 11066 | ||||
| Carroll | 32391 | 41.64% | 44704 | 57.47% | 692 | 0.89% | -12313 | -15.83% | 77787 | ||||
| Cecil | 17371 | 47.56% | 18843 | 51.59% | 310 | 0.85% | -1472 | -4.03% | 36524 | ||||
| Charles | 34305 | 60.89% | 21547 | 38.24% | 491 | 0.87% | 12758 | 22.64% | 56343 | ||||
| Dorchester | 7571 | 58.52% | 5284 | 40.84% | 82 | 0.63% | 2287 | 17.68% | 12937 | ||||
| Frederick | 49336 | 50.60% | 47081 | 48.29% | 1081 | 1.11% | 2255 | 2.31% | 97498 | ||||
| Garrett | 4540 | 38.01% | 7330 | 61.37% | 73 | 0.61% | -2790 | -23.36% | 11943 | ||||
| Harford | 53444 | 48.24% | 56465 | 50.96% | 890 | 0.80% | -3021 | -2.73% | 110799 | ||||
| Howard | 82479 | 63.14% | 46610 | 35.68% | 1538 | 1.18% | 35869 | 27.46% | 130627 | ||||
| Kent | 5117 | 56.54% | 3860 | 42.65% | 73 | 0.81% | 1257 | 13.89% | 9050 | ||||
| Montgomery | 291839 | 72.48% | 106101 | 26.35% | 4702 | 1.17% | 185738 | 46.13% | 402642 | ||||
| Prince George's | 264088 | 85.96% | 39863 | 12.98% | 3270 | 1.06% | 224225 | 72.98% | 307221 | ||||
| Queen Anne's | 9332 | 43.52% | 11964 | 55.80% | 146 | 0.68% | -2632 | -12.27% | 21442 | ||||
| St. Mary's | 18440 | 50.37% | 17802 | 48.63% | 368 | 1.01% | 638 | 1.74% | 36610 | ||||
| Somerset | 5157 | 59.21% | 3501 | 40.20% | 51 | 0.59% | 1656 | 19.01% | 8709 | ||||
| Talbot | 9855 | 53.26% | 8501 | 45.94% | 147 | 0.79% | 1354 | 7.32% | 18503 | ||||
| Washington | 26431 | 47.11% | 29181 | 52.01% | 496 | 0.88% | -2750 | -4.90% | 56108 | ||||
| Wicomico | 19866 | 54.48% | 16348 | 44.83% | 251 | 0.69% | 3518 | 9.65% | 36465 | ||||
| Worcester | 13524 | 54.93% | 10954 | 44.49% | 142 | 0.58% | 2570 | 10.44% | 24620 | ||||
| Total | 1504691 | 65.07% | 783055 | 33.86% | 24816 | 1.07% | 721636 | 31.21% | 2312562 | ||||